The flu vaccine may provide a level of protection against COVID, a new study concludes.
An analysis of patient data from around the world strongly suggests that the annual flu shot reduces the risk of stroke, sepsis and DVT in patients with COVID. Flu-vaccinated COVID patients were also less likely to visit the emergency department and be admitted to the intensive care unit (ICU). The research was presented online at research being presented at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID).
Global COVID vaccination is a daunting challenge and, although production and distribution of vaccines increases daily, some countries are not expected to vaccinate large numbers of their population until the start of 2023.
Recently, several modestly-sized studies suggested that the flu vaccine may provide some measure of protection against COVID.
Ms Susan Taghioff, of the University of Miami Miller School of Medicine, and colleagues carried out a retrospective analysis of data on tens of thousands of patients from around the world to find out more.
In the largest study of its kind, the team screened de-identified electronic health records held on the TriNetX research database of more than 70 million patients to identify two groups of 37 377 patients, from countries including the US, UK, Germany, Italy, Israel and Singapore.
The two groups were matched for factors that could affect their risk of severe COVID-19, including age, gender, ethnicity, smoking and health problems such as diabetes, obesity and chronic obstructive pulmonary disease.
The first group had received the flu vaccine between two weeks and six months before COVID diagnoses. The second group also had COVID but were not vaccinated against flu.
The incidence of 15 adverse outcomes, including sepsis and death, within 120 days of testing positive for COVID was then compared between the two groups. Analysis showed that those not vaccinated for flu were significantly more likely (up to 20%) to have been admitted to ICU.
They were also significantly more likely to visit the Emergency Department (up to 58%), to develop sepsis (up to 45%), to have a stroke (up to 58%) and a deep vein thrombosis (up to 40%). However, the risk of death was not reduced.
It isn’t known exactly how the flu jab provides protection against COVID but most theories centre around it boosting the innate immune system.
The results strongly suggest that the flu vaccine protects against several severe effects of COVID, according to the study authors. Further research is needed to prove this possible link but, in the future, the flu shot could be used to help bolster protection in countries short of COVID vaccine doses.
Senior author Dr Devinder Singh, professor of plastic surgery at the University of Miami Miller School of Medicine, said: “Only a small fraction of the world has been fully vaccinated against COVID to date and, with all the devastation that has occurred due to the pandemic, the global community still needs to find solutions to reduce morbidity and mortality.
“Having access to real-time data of millions of patients is a powerful research tool. Together with asking important questions it has allowed my team to observe an association between the flu vaccine and lower morbidity in COVID patients.
“This finding is particularly significant because the pandemic is straining resources in many parts of the world. Therefore, our research – if validated by prospective randomised clinical trials – has the potential to reduce the worldwide burden of disease.”
Ms Taghioff added: “Influenza vaccination may even benefit individuals hesitant to receive a COVID vaccine due to the newness of the technology.
“Despite this, the influenza vaccine is by no means a replacement for the COVID vaccine and we advocate for everyone to receive their COVID vaccine if able to.
“Continued promotion of the influenza vaccine also has the potential to help the global population avoid a possible ‘twindemic’ – a simultaneous outbreak of both influenza and coronavirus.
“Regardless of the degree of protection afforded by the influenza vaccine against adverse outcomes associated with COVID, simply being able to conserve global healthcare resources by keeping the number of influenza cases under control is reason enough to champion continued efforts to promote influenza vaccination.”
Source: EurekAlert!