- Although coronavirus vaccinations are underway in the UK and US, researchers and health experts still can’t say how long COVID-19 immunity will last.
- Moncef Slaoui, the head of Operation Warp Speed in the US, shared encouraging news about coronavirus immunity from the vaccines in a recent interview.
- The health expert said that vaccines might prevent infection for a limited time, but he expects the drugs to protect against severe COVID-19 for as long as three years after immunization.
Vaccinations with the Pfizer/BioNTech drugs have started in the UK and US, with Europe to follow in late December. Phase 3 trial data showed the drug is 95% effective at blocking COVID-19 and is safe for use. Moderna’s vaccine will be reviewed on Thursday, and the FDA will likely approve it at the recommendation of the independent panel looking at the data. The Moderna drug is also safe to use and 94% effective at blocking the illness. The Moderna vaccine blocked severe COVID-19 in all of the volunteers who were vaccinated and then contracted the virus.
The US is looking to inoculate some 20 million people in December with one of the two vaccines. Regardless of the chosen drug, people who choose to take advantage of vaccines this early will have to get two injections for the best possible protection, spread a few weeks apart. Researchers still can’t say how long vaccine-induced immunity will last, but the chief medical adviser for Operation Warp Speed has one of the best estimations so far.
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Moderna’s announcement that its drug is 100% effective at blocking severe COVID-19 is a detail that people will have to remember during this first phase of immunizations. The first vaccines will not necessarily block infection.
Vaccinated people might still catch the virus from others, and the pathogen will infect cells inside the nose. But the immune response that follows vaccination would prevent the virus from infecting lung cells as effectively as it happens on unvaccinated terrain. This will reduce the risk of severe COVID-19 considerably, and this will save more lives. Also important is that vaccinated people who might be infected after immunization might still be contagious and spread the virus to other people. That’s why face masks and social distancing will be required even for immune people.
Slaoui talked about coronavirus vaccines with MSNBC’s Andrea Mitchell earlier this week via Best Life. That’s where he said that vaccines might not offer great protection against infection, but the protection against severe COVID-19 might last for quite a few years.
“Prevention of infection … may be shorter-lasting, maybe lasts three, four, six months,” Slaoui said. “Prevention of disease, in my humble opinion as an expert, is probably going to last a year or two years, three years.”
Only time will tell how long coronavirus immunity will last, whether it’s after exposure to the illness or after vaccination. A recent study showed that people who survived the illness in early 2020 showed a potent immune response some eight months later. They still had neutralizing antibodies. But more importantly, they had coronavirus-specific B and T white blood cells that could recognize the virus upon reinfection and mount an immediate response. These cells can raise a new generation of antibodies and can kill newly infected cells.
Vaccine makers have started studying B and T cell responses in volunteers who received the drug during clinical trials. The Pfizer/BioNTech vaccine trains the immune system to produce two types of T cells that help with the immune response in an actual infection and selectively kill the infected cells.
We already know that it’s possible to get COVID-19 more than once. It’s reasonable to expect that some vaccinated people will get infected. But if Slaoui’s estimates turn out to be accurate, people could end up getting longer-lasting protection against infection than initially expected.
In previous months, health experts said they’d expect vaccines to provide immunity ranging from six months to up to a year, similar to what happens after infection with one of the other four known human coronaviruses that cause common colds. Others noticed that SARS immunity is still active in some patients, some 17 years later, and that might be a good sign for COVID-19.
Dr. Anthony Fauci said during a November 27th interview that he, too, expected better immunity, but not quite as good as SARS. “From what we know of the duration thus far of immunity, I would be surprised if it turns out to be a 20-year duration, but I would also be surprised if it was less than a year,” Fauci said. “I think it would probably be more than a year.”
To further reduce the risk of infection, countries will need to ensure that a large proportion of the population gets the shots. Some 70% of people will have to be vaccinated for herd immunity to be reached. At that point, the virus should have a much harder time spreading, and return to normal might be possible. Long protection against severe illness combined with a reduced COVID-19 spread would be the best possible way to end the pandemic and ensure the virus can never do as much damage as in 2020.
