You have been vaccinated. They are not. When visiting, is it safe to throw away the tiring mask?
Perhaps. There is growing evidence that vaccines can not only save lives, but can also halt or greatly slow the spread of the COVID-19 virus – predicting a day when we can see each other’s faces again. But Since the findings are not yet definitive, the impact of vaccines on viral transmission remains one of the biggest problems influencing the shape of a post-pandemic world.
Still, UCSF infectious disease expert Dr. Monica Gandhi is so confident of the new evidence that an upcoming family gathering – the elderly vaccinated, the young not – will be mask-free.
“I am convinced by all the data,” she said.
For the general public, she proposes a “step-by-step approach” to our social life. When everyone is vaccinated, people can feel free to interact with each other without restrictions, she said. If some have been vaccinated and others are not, it is safest to keep masking and distance yourself – even if the risk of infection is unlikely or very small. If no one has been vaccinated, all restrictions apply.
Why are tactics so complicated?
It’s because all that’s really known at this point is that a vaccine will prevent you from getting seriously ill or dying.
Does it stop the transmission of the virus? It is noteworthy that none of the vaccine trials was designed to answer this question. In contrast, the focus was on the vaccine’s ability to keep people out of ICUs and morgues.
So there is no definitive evidence yet that vaccines block infection – or that they prevent an inoculated but infected person from passing a secret smoldering virus to others. This is important because people who are “silent spreaders” who never feel sick are feeding the pandemic. There is also concern that vaccines may not be effective against future variants.
If vaccines succeed in blocking transmission, that’s the holy grail and research is going on.
“If the vaccine proves to be 95% effective against asymptomatic transmission, then it’s the full ‘magic bullet’ that will keep us from having to mask,” said Dr. Warner Greene, UCSF professor of medicine and founder and emeritus. director of Gladstone Institute of Virology and Immunology.
Here’s what experts say we’re learning:
• Infection-fighting antibodies are found where we need them to reduce transmission: those mucous membranes that line our nose and airways, home to blobs of virus that spit out when we talk, scream, and sing.
After vaccination, an important subtype of protective antibody called immunoglobulin G (IgG) is found in the blood. But now there is new evidence that IgG is also found in the nose and throat.
There is also promising evidence of another antibody subtype called immunoglobulin A (IgA). While it has not been measured in the COVID-19 vaccine studies, it is known to be generated by other vaccinations – so it should be triggered after our pandemic shots as well. This is important because IgA thrives in the mucus-filled linings of our nose and is used by the body to help fight the COVID-19 virus once it enters our bodies.
“By stimulating antibodies, vaccines can likely clear the virus from your bloodstream, lungs and nasal cavities,” Gandhi said.
• Do you remember the COVID-19 antibody therapy that was used to treat former President Donald Trump? That’s what vaccines do, maybe better.
The treatment – a synthetic monoclonal antibody by drug manufacturer Regeneron – has been proven to speed up the removal of the virus from our airways.
But just consider the difference between mono and stereo music. The Regeneron monoclonal antibody is composed of a single IgG against part of the virus. Vaccines, on the other hand, feel like stereo. They cause so-called polyclonal antibodies – a heterogeneous mix of IgGs against the whole virus.
This diversity is good in the fight against the virus.
“If the monoclonal antibody cleans your nose, it’s reasonable to think that the vaccine’s polyclonal antibodies would, too,” Gandhi said.
• We have not measured how much virus remains in our airways after vaccination. But animal studies offer good news.
Macaques vaccinated with two new vaccines – Novovax and Johnson & Johnson – showed little or no evidence of active virus in their airways. Scientists believe that existing vaccines made by Pfizer and Moderna have the same effect.
• Early data shows that vaccinated people who do become infected harbor about four times less virus than non-vaccinated people who contract the virus. This probably makes them much less contagious.
A research team from Israel’s Maccabi Health Services and the Israel Institute of Technology measured the level of virus in the noses of more than 1,000 people who became infected between 12 and 28 days after their first dose of the Pfizer vaccine, the time when immunity begins to decrease. to build. The amount of virus found was significantly less than in a comparable group of unvaccinated, infected Israelis, the group reported.
With less virus, there is a reduced risk of transmission, Gandhi said.
• In a recent UK trial of the AstraZeneca-University of Oxford vaccine, participants performed weekly nasal swabs at home, which showed that vaccination reduced asymptomatic infections by 49.3%, according to Science magazine. This suggests that the vaccine hinders the spread of viruses.
Moderna has also reported a similar reduction in asymptomatic infections after just one dose of its mRNA vaccine in a subset of its large efficacy study.
When will we get results from a definitive study – confirming the presence or absence of virus by daily wiping the noses of vaccinated and unvaccinated? That work is underway.
“Unless we answer this question, we are a masked society,” Dr. Myron Cohen, infectious disease physician at the University of North Carolina, Chapel Hill, to the journal Science. He heads the government’s COVID-19 prevention network. “We have to tackle this to become maskless.”