Influenza Vaccine May Boost Immunity Against Coronavirus

RIO DE JANEIRO, BRAZIL – The flu vaccine may boost the immune system to fight and eliminate the novel coronavirus. This is suggested in a new preliminary study, which for the first time analyzed the effects of the flu vaccine in the presence of the new SARS-CoV-2 virus at the molecular level. The in vitro study conducted in the Netherlands also suggests that the flu vaccine protects against coronavirus infection by up to 39 percent.

Until now it was unclear whether vaccines against influenza and other diseases could improve or worsen the prognosis of people infected with Covid-19, or even if they would be able to help prevent contagion. In recent months, several studies have been reporting the positive effects of the flu vaccine.

In Italy, it was found that the elderly immunized against the flu recorded lower mortality rates from Covid-19 than the unvaccinated in this age group, according to a study already reviewed by independent experts and published in a scientific journal. The same team found similar data in the U.S.A., although this study has not yet been peer reviewed. Other works follow the same line.

However, there are still doubts. There is another preliminary study that seems to detect the opposite effect: higher Covid-19 incidence and mortality among immunized individuals. Likewise, it was observed that the tuberculosis vaccine can also partially protect against the coronavirus. Several clinical trials with patients are in progress in an attempt to demonstrate this positive effect.

The new study concludes that the flu vaccine reinforces the immune system’s first line of defense – known as innate immunity – and points out why. This first line, triggered soon after a pathogen enters the body, features cells capable of identifying the threat, sending out a widespread warning signal for other soldiers to report at the site of infection, along with natural killer cells capable of destroying cells that have already been infected.

The work is based on blood samples from healthy individuals, to which a quadrivalent flu vaccine – designed to protect against four different flu viruses – has been added first, followed by the   SARS-CoV-2 coronavirus. The work shows a boosted innate immune response and the secretion of certain types of cytokines.

Although these immune system proteins are associated with severe prognosis and even death by Covid-19 in already very sick patients, in the early stages of infection these molecules would help build a more balanced reaction of the immune system.

In addition, researchers suggest that the flu vaccine helps the first line of immunity bind better to the second line, which includes the production of antibodies, proteins capable of blocking the virus from infecting further, and immune cells capable of remembering the virus for months or years, destroying it if it reappears.

Led by Mihail Netea of the Medical Center of the University of Nijmegen (Netherlands), the work also studied the incidence of Covid-19 among over 10,000 healthcare professionals, 184 of whom were infected in the university hospital, and compares it with other hospitals in the country. The study shows that the risk of Covid-19 infection is approximately 39 percent lower among those who had previously been vaccinated against influenza.

“This is an epidemiological study, not a randomized, prospective clinical trial, so we can’t be completely sure that the flu vaccine will have as great an effect as the one observed,” explains Netea. “In any case, it is possible that this protection will actually occur and that the [flu] vaccine will reduce the spread of Covid-19,” he adds. The work is currently being reviewed for publication in a scientific journal.

Those responsible for the work caution about some limitations in their study. For instance, it is possible that the risk of infection is higher for some healthcare professionals than for others, regardless of whether or not they are vaccinated, which may affect the results. In addition, there is a potential bias, as in general, people who are vaccinated are much more cautious and concerned with their health and with possible infection than those who are not immunized.

“With these data and bearing in mind that there are still months to go before an effective vaccine against Covid-19 is widely available, the flu vaccine can not only help contain this virus, but also the burden of Covid-19 infections, particularly in hospitals,” concludes the study.

“These data show us that the flu vaccine can boost natural immunity,” points out Marcos López, president of the Spanish Society of Immunology. Moreover, the work noted an additional immunological effect if, in addition to the flu vaccine, the tuberculosis (BCG) vaccine was administered.

“The protective effect observed is moderate, but the important point is that it is proven for the first time in vitro that this vaccine enhances trained immunity,” explains Carmen Cámara, immunologist at La Paz Hospital in Madrid. Until now, this was demonstrated with the BCG tuberculosis vaccine and with live vaccines.

“In the two years following the administration of these vaccines, the innate system operates with increased intensity against other viral infections. The mechanism is intended to train the innate immune system cells as natural killers, macrophages or monocytes to react more quickly and intensely against other viral infections.”

This study “provides an additional reason to be vaccinated against influenza, but it is not enough to recommend the flu vaccine to the whole population,” emphasizes Cámara. In Brazil, the Ministry of Health recommends the vaccine against influenza for people over 55, the immunocompromised, and healthcare professionals. Children from 6 months onwards, pregnant women, people with disabilities, and public school teachers are also on the recommended list.

“The effects of immunity trained with the BCG [tuberculosis], with other vaccines, and even with the DTP [diphtheria, tetanus, and pertussis] have been described, but it must be shown,” warns África González, immunologist at the University of Vigo. “It’s a good idea to test this; it will open the door to new studies.”

Source: El País

More: Brazil news in English, every day from The Rio Times.

This article was produced by The Rio Times’ automated newsroom system. How we use AI · Report an error