Will we need COVID-19 vaccines every year? Maybe not

Now that the Food and Drug Administration has approved COVID-19 vaccine recalls for all adults, people are looking to what next year has in store for COVID-19 and the future of vaccination. And many questions remain.

At the New Economy Forum this week in Singapore, Bill Gates said he expects that by mid-2022, deaths from COVID-19 and infection rates in general will drop lower than those of seasonal flu, as long as a dangerous new variant does not. arise. That’s an even shorter timeframe than what the pharmaceutical chiefs predicted. In September, Moderna CEO Stéphane Bancel said the pandemic was set to end in a year. Also in September, Pfizer CEO Alan Bourla told ABC’s This week that he was okay with people being able to resume their normal lives in a year, but he predicted that the COVID-19 variants would continue to circulate. “I think the most likely scenario is annual revaccination,” he said.

Pharmaceutical companies are already preparing for a world in which annual COVID-19 vaccination is routine. Novavax (a Maryland-based biotech company) and Moderna are both developing a single shot that covers COVID-19 and the flu. Pfizer, meanwhile, is in the process of developing a separate mRNA-based influenza vaccine, which could be given at the same time as a COVID-19 vaccine.

Alessandro Sette, professor at the Center for Infectious Diseases and Vaccines at the Institute of Immunology of La Jolla, predicts a gradual return to normal, however long it takes. What could complicate matters, he says, is the large number of people who are not vaccinated and have not developed immunity through infection.

“We have millions of people in this predicament all over the world,” he said. “Where there are millions and millions of people susceptible to infection, it could lead to a situation where infection rates soar. The solution is to increase immunization around the world. “

Still, Sette doesn’t think SARS-COV-2 – the coronavirus – will require an annual injection. “The simple question, will we need a booster like in the case of the flu? The answer is no, ”he says. The reason a different influenza vaccine is developed each year is that the flu itself is different each year, he explains. In contrast, the reason the FDA approved a COVID-19 recall is not because the virus has changed, but because immunity is waning. So, at this time, there is no reason to believe that the annual COVID-19 vaccination will necessarily become routine. “At the same time,” Sette admits, “we don’t really know.

Will covid become like the flu?

Here’s why COVID-19 and the flu may require different vaccination strategies. Sette says that during the summer and spring months, when influenza transmission typically declines among Americans, she incubates in another host: birds. “It evolves in birds and then comes back in winter to re-infect humans,” he explains. COVID-19 did not do this. And, he says, that doesn’t seem to change as much as the flu virus.

The other reason is related to the functioning of the human immune system. “The immune system learns something once. . . it may be remembered, ”says Sette. “If he sees [something] twice is a better memory. And after a third time, the memory continues to increase, such as repeating the same lecture or seeing the same movie three times. It goes without saying that a third blow will have a more lasting effect. Sette notes that after a third hepatitis B vaccination, for example, immunity lasts forever.

A longer interval between vaccinations gives better results.

While immunity may have waned in people who have received two doses of Pfizer and Moderna vaccines, a third dose may have stronger effects. According to Sette, the time between when the shots were received can make a difference in their effectiveness. “The two vaccines that were given for most vaccines were given quite close to each other, a few weeks or three weeks apart. It’s not usually the best way to do it or the way it’s usually done, ”he says, noting that the compressed schedule was a response to the urgency of the situation. But having a longer interval between vaccinations works better, he says, and there is reason to believe that a third vaccination will provide both more effective and longer lasting results.

Dr William Moss, executive director of the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health, agrees that an annual COVID-19 vaccine is unlikely. He says the only reason public health officials would recommend additional vaccination is if immune protection is not sustained enough from the first three vaccines. But whether or not the protection is sufficient depends on how public health officials define “sustainable”. If the goal is to prevent serious illness, hospitalizations and death, we may not need more than this latest reminder, says Moss. The immune systems of people who receive three injections – and those who have been infected with COVID-19 – may have learned enough to prevent serious infection with COVID-19 indefinitely.

In that case, COVID-19 could become one of the many respiratory illnesses we fight every year without annual vaccination. “If we really expect our vaccines to prevent asymptomatic infections, mild infections and completely prevent transmission, that’s a very high bar for a vaccine,” says Moss. In the latter case, he could see drug companies developing something like a nasal spray vaccine, which creates an immune response at the site of infection.

What if there was another coronavirus?

A new variant of COVID-19 could derail both public health efforts to bring the virus under control and, possibly, new, highly effective mRNA vaccines developed to combat it. Delta has been the most dangerous variant so far, but despite its virulence, it has not been able to escape the protection afforded by current vaccines. Moss says that while it is possible that a new variant emerges that is not susceptible to current vaccines, “there are evolutionary constraints on the virus.”

It has to do with the spike protein in SARS-COV-2, which allows the virus to attach itself to our cells. MRNA vaccines direct human antibodies to search for and neutralize the spike protein to prevent infection. “The virus can – and I’m sure it did – mutate from that, but these viruses can’t get into cells,” says Moss.

That said, if there is an increase in breakthrough infections or a need for a new coronavirus vaccine, we might see a vaccine that targets multiple variants. “A mixture of different antigens from different strains of influenza is already in common use,” says Sette of the La Jolla Institute of Immunology. In fact, researchers are already exploring a universal vaccine against the coronavirus that would fight not only other variants of COVID-19, but all viruses in this family.

“There is no evidence that you would need a vaccine against different variants of SARS mixed together,” Sette said. “But if it did, it’s doable.”

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