Category: Vaccines

Categories : Diseases, Syndromes and Conditions VaccinesTags :

Limpopo Measles Outbreak Continues amid Low Vaccination Rates

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Since 11 October 2022, the National Institute for Communicable Diseases (NICD) seven measles cases have been detected in Greater Sekhukhune District in Limpopo province within 30 days, as of 21 October. 

Infected individuals ranged from 9 months to 24 years. One child was fully vaccinated for measles, with two measles doses given in 2019. One child was unvaccinated, and the other five measles cases had unknown vaccination history. One measles case was hospitalised while one other had a complication that led to pneumonia.

District and provincial health officials have started a public health response. This includes enhanced surveillance for measles, contact tracing, screening for suspected cases using a case definition followed by collection of blood and throat swabs for measles diagnostic testing, and reviewing medical records to pick up missed cases. Vaccinations are underway for those exposed to suspected or confirmed cases.

The measles immunisation coverage data for the Greater Sekhukhune district showed a decrease of 87% to 64% for measles dose 1 and 86% to 60% for measles dose 2 from 2017 to 2022. This is below the 95% coverage needed to achieve herd immunity. A survey is being done to validate the vaccination data provided to the province and investigate factors that might be contributing to the measles outbreak.  Community awareness and health promotion by healthcare workers is continuing in the district to inform the public about the spread of measles and interventions to prevent disease. Measles vaccination has been initiated for children under 15 years to increase the measles immunity in the community and to prevent further spread of measles.

Clinicians should continue to be on the alert for measles cases, especially in Limpopo Province, as large measles outbreaks are occurring in sub-Saharan Africa, including in neighbouring countries.

Signs and Symptoms

Measles is a highly contagious disease caused by a virus of the paromyxovirus family. Patients with measles present with fever and a rash. The rash looks like small, red, flat spots over the body. The rash does not form blisters, nor is it itchy or painful. Other signs include cough, conjunctivitis and coryza. Complications of measles can include diarrhoea, dehydration, encephalitis, blindness and death. Other measles complications are pneumonia, scarring of the cornea (kerato-conjunctivitis), and rarely encephalitis. Complications are more serious in very young children (under 2 years) or who are malnourished.

Clinicians and caregivers should check children’s road-to-health booklets to ensure measles vaccinations are up to date. Suspected measles cases should be notified on the NMC system. Click here to access the Case Notification form 

Source: NICD

Categories : Cardiovascular Disease VaccinesTags :

Flu Vaccine May Reduce Ischaemic Stroke Risk

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Receiving an annual flu vaccination may be linked to a reduction in risk of ischaemic stroke, according to a study which appears online in the journal Neurology.

“Studies have shown that getting the flu increases your risk of having a stroke, but research is still being collected on whether getting the flu vaccine can help protect against a stroke,” said study author Francisco J. de Abajo, MD, MPH, PhD, of the University of Alcalá in Madrid. “This observational study suggests that those who have a flu shot have a lower risk of stroke. To determine whether this is due to a protective effect of the vaccine itself or to other factors, more research is needed.”

In their study, the researchers accessed a health care database in Spain, identifying 14 322 participants aged 40 years and over with a first stroke over a 14-year period. Each person who had a stroke was matched to five people of the same age and sex who did not have a stroke.

Then the researchers looked at whether people had received the influenza vaccine at least 14 days before the stroke or before that same date for those who did not have a stroke.

A total of 41.4% of those who had a stroke had received the flu vaccine, compared to 40.5% of those who did not have a stroke – seemingly indicating that the flu jab added to risk. But those vaccinated were more likely to be older and to have other stroke risk factors such as hypertension and high cholesterol. Once these were adjusted for, the researchers found that those who received a flu shot had a 12% reduced stroke risk.

The pneumonia vaccine was also investigated for any effect on the risk of stroke, but none was found.

“These results are yet another reason for people to get their yearly flu shot, especially if they are at an increased risk of stroke,” de Abajo said. “To be able to reduce your risk of stroke by taking such a simple action is very compelling.”

Since the study was observational, it only shows an association and cannot prove a causal link. Other unmeasured factors could also mediate stroke risk,

Source: American Academy of Neurology

Categories : VaccinesTags :

Oxford’s New Malaria Vaccine is ‘World Changing’

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Mosquito, a malaria parasite vector
Photo by Егор Камелев on Unsplash

A malaria vaccine developed by Oxford University has been described as “world changing” following its successful trial in children in Burkina Faso. Their results of their double-blind randomised controlled trial were published yesterday in The Lancet Infectious Diseases.

The researchers had previously reported that in children, the R21/Matrix-M malaria vaccine reached the WHO-specified goal of 75% or greater efficacy over 12 months.

To test the immunogenicity, and efficacy results at 12 months after administration of a booster vaccination, the researchers conducted a trial was done in children aged 5–17 months in Burkina Faso, who had written informed consent provided by their caregivers. Eligible children were randomised to receive three vaccinations of either 5 μg R21/25 μg Matrix-M, 5 μg R21/50 μg Matrix-M, or a control vaccine (the Rabivax-S rabies vaccine) before the malaria season, with a booster dose 12 months later. Exclusion criteria included any existing clinically significant comorbidity or receipt of other investigational products.

Vaccine safety, efficacy, and a potential correlate of efficacy with immunogenicity, measured as anti-NANP antibody titres, were evaluated over one year following the first booster vaccination. Efficacy analyses were performed for all participants who received the primary series of vaccinations and a booster vaccination.

Between June 2, and July 2, 2020, 409 children returned to receive a booster vaccine, which was the same received in the primary series of vaccinations. R21/Matrix-M had a favourable safety profile and was well tolerated. Vaccine efficacy remained high in the high adjuvant dose (50 μg) group, similar to previous findings at one year after the primary series of vaccinations. Following the booster vaccination, 51% of children receiving R21/Matrix-M with low-dose adjuvant, 39% of children receiving the same but with high-dose adjuvant, and 86% of 140 children who received the rabies vaccine developed clinical malaria by 12 months.

Vaccine efficacy was 71% in the low-dose adjuvant group and 80% in the high-dose adjuvant group. In the high-dose adjuvant group, vaccine efficacy against multiple episodes of malaria was 78%, and 2285 cases of malaria were averted per 1000 child-years at risk among vaccinated children in the second year of follow-up. Among these participants, at 28 days following their last R21/Matrix-M vaccination, titres of malaria-specific anti-NANP antibodies correlated positively with protection against malaria in both the first year of follow-up (Spearman’s ρ –0·32 [95% CI –0·45 to –0·19]; p = 0·0001) and second year of follow-up (–0·20 [–0·34 to –0·06]; p = 0·02).

A booster dose of R21/Matrix-M at 1 year following the primary three-dose regimen maintained high efficacy against first and multiple episodes of clinical malaria. Furthermore, the booster vaccine induced antibody concentrations that correlated with vaccine efficacy. The trial is ongoing to assess long-term follow-up of these participants and the value of further booster vaccinations.

Speaking to BBC News, Prof Katie Ewer said that “this is not like COVID where we have seven vaccines straight away that will work… it’s much, much harder”. This malaria vaccine is the 14th that she has worked on, and it was “incredibly gratifying” to get this far and “the potential achievement that this vaccine could have if it’s rolled out could be really world-changing”.

The Oxford-developed vaccine shares similarities with the current, approved malaria vaccine from GSK: both target the first stage of the parasite’s lifecycle by intercepting it before it can establish itself in the liver.

The vaccines use a combination of proteins from the malaria parasite and the hepatitis B virus, but the Oxford vaccines has a more malaria proteins, which may help the immune system to focus on malaria rather than the hepatitis.

The trial is continuing for a further 2 years to assess both the potential value of additional booster vaccine doses and longer-term safety.

Categories : VaccinesTags :

One Step Close to a Universal Flu Vaccine

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Syringe withdrawing from vaccine vial
Photo by Mufid Majnun

A new universal flu vaccine protects against diverse variants of both influenza A and B viruses in mice, according to a new study published in the journal PLOS Pathogens.

The researchers designed a single, universal influenza vaccine candidate with key cross-protective, less variable parts of the influenza A and B viruses: multi-neuraminidase protein subtypes known to be major antiviral drug targets and the universally conserved M2 ectodomain protein.

The researchers, from the Institute for Biomedical Sciences at Georgia State University, report that mice vaccinated with an immune stimulating virus-like particle displaying multiple neuraminidase subtypes and conserved M2 portions of antigens were protected against influenza A seasonal variants and pandemic potential viruses (H1N1, H5N1, H3N2, H9N2 and H7N9) and influenza B (Yamagata and Victoria lineage) viruses containing substantial antigenic variations.

Viral variants emerge when flu pathogens change their major surface haemagglutinin protein that binds to host receptor molecules. Continuous mutational changes in the flu haemagglutinin proteins result in immune escape and sever disease.

Current influenza vaccines are based on strain-specific immunity to haemagglutinin, a highly variable target of immune protection. The effectiveness of the seasonal vaccine is unpredictable and could be below 20% because of continuous changes in haemagglutinin proteins. Influenza therefore remains a significant risk to human health worldwide.

“We developed a single, universal vaccine entity that induced immunity to conserved M2 ectodomain and multi subtype neuraminidase proteins and was found to be effective in conferring broad cross protection against antigenically diverse influenza A and B viruses in young and aged mice,” said Professor Sang-Moo Kang, senior author of the study. “This study provides impactful insight into developing a universal influenza vaccine inducing broad immunity against both flu A and B variants in young and aged populations.”

This study supports a novel strategy for creating a universal vaccine against influenza A and B viruses. A single construct displaying multiple cross protective proteins has the capacity to induce immunity to M2 and multi-subtype neuraminidase proteins of influenza A and B viruses, as well as offer broad cross protection against sickness and mortality under lethal flu virus challenges in mice, according to the study.

Vaccinating mice with this universal vaccine candidate induced broad neuraminidase inhibition, M2 ectodomain specific antibodies and T cell immune responses. Comparable cross protection was induced in aged mice.

The study warrants further testing of this unique, universal va ccine candidate in ferrets, which have similar respiratory tracts to humans.

Source: Georgia State University

Categories : Paediatrics VaccinesTags :

Infant BCG Vaccination Only Protects up to Five Years of Age

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Syringe withdrawing from vaccine vial
Photo by Mufid Majnun

A study has found that the Bacillus Calmette-Guérin (BCG) vaccine, when administered in infancy, only protects against tuberculosis (TB) in children under five years of age. The findings, published in The Lancet Global Health, showed that the vaccine provided no protection among adolescents or adults in the study.

Despite the age and widespread use of the BCG vaccine, debate continues on how effective it is in preventing TB, and the duration of immunity after it is administered in infancy. And as experts study and propose new TB vaccines to supplement the BCG vaccine, an important consideration is the age at which these new vaccines should be administered to high-risk populations.

Gathered from 20 years of recent studies, this analysis provides new insight and clarity on these issues.

These results suggest that protectiveness from the BCG vaccine may begin to wane as children get older and, thus, children over 10 years old and adults should receive a booster BCG vaccine for immunity against TB beyond childhood. Unfortunately, a BCG booster has limited efficacy, so new vaccines are needed.

“Unlike many of the mRNA COVID vaccines, which we know are highly effective, there is widespread debate on the BCG vaccine’s effectiveness and duration of protection, as well as whether the vaccine only works in selective settings,” explained study lead author Leonardo Martinez, assistant professor of epidemiology at Boston University School of Public Health. “Our findings indicate that BCG vaccination is effective at preventing tuberculosis in young children. Since tuberculosis in children is a highly debilitating and severe disease, BCG vaccination should continue to be used.”

However, since the results show that the vaccine was ineffective in adolescents and adults, “boosting immunoprotection is needed for older populations,” Asst Prof Martinez said. “Novel vaccines are urgently needed to supplement BCG vaccination in high-burden settings.”

Most studies on this subject were done over 50 years ago, with varying results, and primarily in settings with a relatively low burden of the disease. This new analysis presents data over the past 10 years, from high-burden settings in 17 countries, including South Africa, China, Vietnam, Indonesia, Uganda, The Gambia, and Brazil.

For the study, Asst Prof Martinez and colleagues analysed individual-level data from 26 longitudinal studies that included nearly 70 000 participants exposed to TB from 1998 to 2018. The researchers examined the impact of BCG vaccination for all TB disease, as well as specifically for pulmonary and extrapulmonary TB. The analysis examined variability across the studies, including the use of skin and blood TB infection tests, and accounted for potentially confounding factors such as HIV, exposure status, and history of prior TB, amongst others.

Among all children under 5 years old, BCG vaccination was 37% effective. The researchers did not find conclusive evidence that the vaccine was protective among children over 10 or among adults. When focusing only on pulmonary TB, BCG vaccination was 19% effective, however this effect was also only among young children.

The researchers stress that substantial investment in TB vaccine development is critical to controlling global TB.

“We urgently need vaccines that are effective against tuberculosis in adults,” said study co-author C. Robert Horsburgh, professor of epidemiology. “There are a number of promising TB vaccine candidates under study and we hope that one or more of them will prove effective.”

Source: Boston University

Categories : VaccinesTags :

New Tuberculosis Vaccine Passes Safety Hurdle in SA Trial

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Tuberculosis bacteria
Tuberculosis bacteria. Credit: CDC

The only vaccine currently available against tuberculosis, Bacillus Calmette Guérin (BCG), is not equally effective against all types of tuberculosis. A clinical trial in South Africa has now shown that the new vaccine candidate VPM1002, decades in development, is equally safe for newborns with and without HIV exposure and has fewer side effects compared to BCG.

First used 100 years ago, the BCG vaccine against the disease contains attenuated pathogens of cattle tuberculosis. “We know that BCG can prevent so-called tuberculous meningitis and miliary tuberculosis in infants with a 75 to 86 percent effectiveness rate. But this is not the case for the most common form of the disease, pulmonary tuberculosis, in all age groups. Here, BCG is only insufficiently effective,” explained Max Planck researcher Stefan H.E. Kaufmann, who developed the vaccine with his team.

Since the 1990s, the infection biologist and his team have been working on an improved next-generation vaccine, called VPM1002. To achieve this, the researchers genetically modified the attenuated BCG vaccine strain so that immune cells can better recognise the pathogens. “We developed VPM1002 in no small part to combine increased safety with improved efficacy for immunocompromised children,” Kaufmann said.

Vaccine candidate VPM1002 is safe

The group of immunocompromised children includes, for example, HIV-exposed infants born to HIV-positive mothers. In a clinical trial in South Africa, researchers compared VPM1002 with BCG in HIV-exposed and non-HIV-exposed newborns. The study examined both the safety and the immunogenicity associated with the formation of immune cells and immunostimulatory proteins. The study, published in Lancet Infectious Diseases, concluded that VPM1002 is safe in both HIV-exposed and non-HIV-exposed newborns, has fewer side effects than BCG, and elicits a similar immune response.

In the randomised phase II double-blind study in South Africa, 416 eligible newborns were randomly selected and vaccinated before day 12 of life. 312 of them received VPM1002, and 104 received the BCG vaccine. As the study showed, VPM1002 triggered fewer vaccine-related adverse reactions than BCG. This was true for reactions occurring at the injection site, such as scarring and abscess formation, as well as enlargement of lymph nodes. This finding is important because local and regional reactions after vaccination are among the limitations of the BCG vaccine, Kaufmann points out.

Newborns with or without HIV exposure showed similar immunogenicity with both vaccines, though starting at six weeks of age, the BCG-triggered immune response was greater than in even younger infants.

Phase III study investigates protection

“Studies such as those described here examine a vaccine’s immunogenicity, but not its protection. For the latter, we have already developed a larger phase III clinical trial and have successfully enrolled mothers with their newborns to participate. Now the clock is ticking,” Kaufmann said. He expects initial results showing whether VPM1002 can provide comparable or better protection than existing BCG vaccines in about three years. In addition, VPM1002 vaccine is currently in two other phase III clinical trials in India for protection against tuberculosis, which expected to be completed in 2023 and 2024.

Source: Max-Planck-Gesellschaft

Categories : COVID VaccinesTags :

Vaccine Acceptance is Increasing Around the World

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Image of a syring for vaccination
Photo by Mika Baumeister on Unsplash

COVID vaccine acceptance across much of the world increased by 3.7% between 2020 and 2021, according to a new study published in Nature Communications.

In a June 2021 survey of over 23 000 individuals across 23 countries, the researchers found that 75.2% of respondents reported vaccine acceptance, up from 71.5% one year earlier.  

The study was carried out during a year of substantial but very unequal global COVID vaccine availability and acceptance, which required new assessments of the drivers of vaccine hesitancy and the characteristics of people not vaccinated.

Vaccine hesitancy was most consistently associated with concerns about vaccine safety and efficacy and mistrust in vaccine development. Other factors associated with vaccine hesitancy varied by country and included personal experience with COVID (eg, sickness or loss of a family member) and demographic characteristics (eg, gender, education, and income).

The authors also found that vaccine hesitancy was not associated with a country’s current COVID case burden and mortality. In June 2021, vaccine hesitancy was reported most frequently in Russia (48.4%), Nigeria (43%), and Poland (40.7%), and least often in China (2.4%), the UK (18.8%), and Canada (20.8%).

“In order to improve global vaccination rates, some countries may at present require people to present proof of vaccination to attend work, school, or indoor activities and events,” said CUNY SPH Senior Scholar Jeffrey Lazarus. “Our results found strong support among participants for requirements targeting international travellers, while support was weakest among participants for requirements for schoolchildren.”

Those who were vaccine-hesitant were also less likely to express support for vaccine mandates. “Importantly, however, recommendations by a doctor, or to a lesser extent by an employer, might have an impact on a respondent’s views on vaccination in some countries,” said CUNY SPH Dean Ayman El-Mohandes.

Although some countries are currently disengaging from evidence-based COVID control measures, the disease has by no means been controlled or ended as a public health threat. The authors note that for ongoing COVID vaccination campaigns to succeed in improving coverage going forward, substantial challenges remain. These include targeting those reporting lower vaccine confidence with evidence-based information campaigns and greatly expanding vaccine access in low- and middle-income countries.

The Role of Social Networks

The researchers also held a meeting to explore vaccine messaging. According to data presented from a European survey carried out by the Vaccine Confidence Project, the population group most exposed to social networks, ie people under 24, with secondary or university studies and living in urban areas, are the most reluctant to be vaccinated. Additionally, messages that call for vaccination as a “moral obligation” are strongly rejected compared to those that call for “protection,” which are more commonly well received.

As with previous studies, humour was shown to be one of the most effective ways to convey anti-vaccine messages. Therefore, participants in the meeting agreed on the need to disseminate the benefits of vaccines using this same tool, but without making fun of those who have mistaken beliefs about vaccines. In the face of misinformation, it is important to improve information on vaccination using simple language and channels that reach the population, such as social networks, the participants concluded.

Source: CUNY Graduate School of Public Health and Health Policy

Categories : VaccinesTags :

New Universal Flu Vaccine Offers Broad Protection, Study Finds

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By focusing on key parts which remain stable over time, scientists have created a universal flu vaccine that offers broad cross protection against different strains and subtypes of influenza A viruses in both young and old populations, according to a new study reported in npj Vaccines.

The researchers developed the universal flu vaccine by genetically linking two highly conserved portions of the virus: the extracellular domain of matrix 2 (M2e) and the stalk protein found in influenza A H3N2 viruses. The findings show that vaccinating against M2e-stalk protein induced broad protection against different influenza virus strains and subtypes by universal vaccine-mediated immunity in adult and aged mice.

Developing effective influenza vaccines has been a challenge because the head portion of the influenza virus is constantly mutating. When comparing the H1N1 and H3N2 influenza A viruses, particular challenges exist in H3N2 subtypes because of stalk mutations in circulating strains and the unstable structure of stalk proteins for H3N2 viruses. These drawbacks have been difficult to overcome in developing effective H3 stalk-based vaccines.

In the past decade, vaccine effectiveness against H3N2 hovered around 33%, and during the 2014–2015 flu season, it dropped to 6%. New mutations of H3N2 variants emerged with increased virulence. Also, the outbreak of H7N9, another influenza A subtype, caused concern for potential pandemics. Therefore, developing an effective vaccine to protect against these viruses is a high priority.

“The M2e-stalk protein, for the first time, could be easily produced in bacterial cell cultures at high yields and was found to confer protection against heterologous and heterosubtypic cross-group subtype viruses (H1N1, H5N1, H9N2, H3N2 and H7N9) at similar levels in adult and aged mice,” said Dr Sang-Moo Kang, senior author of the study and a professor in the Institute for Biomedical Sciences at Georgia State. “These results provide evidence that M2e-stalk genetic fusion proteins can be produced in a large scale at low cost and developed as a universal influenza A virus vaccine candidate for young and aged populations.”

The study found this novel M2e-stalk protein vaccine induced M2e and stalk-specific Immunoglobulin G (IgG) antibodies that recognised antigenically diverse influenza viral antigens on virus particles and on the infected cell surface. The vaccine also stimulated protective cellular T cell immunity and effective lung influenza viral clearance in mice.

Source: Georgia State University

Categories : Ageing VaccinesTags : 1 Comment

Flu Jab May Protect Against Developing Alzheimer’s

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Old man
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In a study with nearly 2 million older adults, those who received at least one influenza vaccine were 40% less likely than their non-vaccinated peers to develop Alzheimer’s disease over four years of follow-up, according to a new study from UTHealth Houston.

An early online version of the paper detailing the findings is available in advance of its publication in the Journal of Alzheimer’s Disease in August.

“We found that flu vaccination in older adults reduces the risk of developing Alzheimer’s disease for several years. The strength of this protective effect increased with the number of years that a person received an annual flu vaccine – in other words, the rate of developing Alzheimer’s was lowest among those who consistently received the flu vaccine every year,” said first author Avram S. Bukhbinder, MD. “Future research should assess whether flu vaccination is also associated with the rate of symptom progression in patients who already have Alzheimer’s dementia.”

The study comes two years after UTHealth Houston researchers found a possible link between the flu vaccine and reduced risk of Alzheimer’s disease. This new study analysed a much larger sample than previous research, including 935 887 flu-vaccinated patients and 935 887 non-vaccinated patients.

During four-year follow-up appointments, about 5.1% of flu-vaccinated patients were found to have developed Alzheimer’s disease. Meanwhile, 8.5% of non-vaccinated patients had developed Alzheimer’s disease during follow-up.

These results underscore the strong protective effect of the flu vaccine against Alzheimer’s disease, according to Bukhbinder and Schulz. However, the underlying mechanisms behind this process require further study.

“Since there is evidence that several vaccines may protect from Alzheimer’s disease, we are thinking that it isn’t a specific effect of the flu vaccine,” said Professor Paul. E. Schulz, MD, senior author of the study. “Instead, we believe that the immune system is complex, and some alterations, such as pneumonia, may activate it in a way that makes Alzheimer’s disease worse. But other things that activate the immune system may do so in a different way – one that protects from Alzheimer’s disease. Clearly, we have more to learn about how the immune system worsens or improves outcomes in this disease.”

Past research has uncovered a decreased risk of dementia associated with prior exposure to various adulthood vaccinations, including those for tetanus, polio, and herpes, in addition to the flu vaccine and others.

Additionally, as more time passes since the introduction of the COVID vaccine and longer follow-up data becomes available, Dr Bukhbinder said it seeing if there is a similar link between COVID vaccination and the risk of Alzheimer’s disease.

Source: The University of Texas Health Science Center at Houston

Categories : Diseases, Syndromes and Conditions VaccinesTags :

Why The Malaria Vaccine Quickly Loses its Effectiveness

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More than 600 000 people worldwide still die from malaria every year, according to the WHO. The vast majority of fatal cases of malaria are caused by the single-celled pathogen Plasmodium falciparum, which so far has only one approved vaccine against it, and its efficacy, which is already rather low, is also short-lived. A new study in Science Immunology may have the explanation: a lack of cross-reactivity in T helper cells.

The vaccine targets CSP, the quantitatively dominant protein on the surface of the “sporozoites”. Sporozoites are the stage of the malaria pathogen which is transmitted with the bite of the mosquito and enters human blood. “To improve the vaccine, we need to understand which protective antibodies are induced by the immunisation. But the production of such antibodies depends to a large extent on help from the so-called follicular T helper cells,” explained Dr Hedda Wardemann, immunologist and senior author of the study. “They ensure that B cells transform into antibody-producing plasma cells and memory B cells.”

To study the T helper cell response against CSP in detail, Dr Wardemann’s team examined the blood of volunteers infected with killed P. falciparum sporozoites from the vaccine strain. The volunteers were of European descent and had no prior contact with malaria pathogens. The researchers analysed the induced Plasmodium-specific follicular T helper cells at the single cell level. They focused on which sequences of CSP are recognised by the T helper cells’ receptors.

The analyses revealed that the T-cell receptors mainly targeted amino acids 311 to 333 of the CSP. But the researchers were stunned by another finding: there was virtually no cross-reactivity between the individual T-cell clones. “The receptors highly specifically bind only the CSP epitopes of the vaccine strain used. Even deviations of only a single amino acid component were not tolerated in some cases,” Dr Wardemann explained.

The immunologist points out that in the natural population of P. falciparum, sequence polymorphisms occur to a high degree in this region of the CSP. “The specificity of the T-cell clones prevents the constantly recurring natural infections with the pathogen from acting as a natural ‘booster.’ This could possibly explain why the protective effect of the malaria vaccine wears off so quickly,” Dr Wardemann said. The researcher recommends that further development of the vaccine should test whether inducing a broader spectrum of T helper cells could generate longer-lasting immune protection.

Source: German Cancer Research Centre