As hospitalizations plateau and Covid 19 infections decrease in the US, health experts say the vast majority of people stricken with the latest strains of the virus are the unvaccinated.
At an EMS round table on Jan 21, Dr. Ben Neuman, a virologist at Texas A&M and Dr. Dali Fan, a Clinical Professor at UC Davis, answered questions on the pandemic’s status, the science behind vaccination and its protective effects, new variants in the pipeline, and the possibilities of Covid19 becoming endemic, like the flu. (Answers have been edited for clarity.)
The status of the pandemic
Dr. Fan: Omicron started in South Africa and went to England very quickly. The hallmark of Omicron is that cases peak in the first week or two and drop quickly as well. This pattern is reflected in the US. From New York, Omicron spread westwards to the west coast. California is peaking right now as cases slowdown in NY, and will taper off in early February. In Massachusetts almost a 100% of new cases are Omicron, but the surge of cases in the western regions are a combination of Delta and Omicron.
Dr. Neuman: At the moment in Texas and other hard-hit states, the one confounding factor is that testing centers are overwhelmed, so we are under reporting because we are under-testing. The wave began in the northern US so perhaps the south will follow a month later.
University of California, Davis
The effectiveness of boosters and vaccines
Dr. Fan: Data from Israel and South Africa shows that protective effective of two shots wanes from 80% to 30% (for the Pfizer vaccine) but a booster re-elevates immunity to about 70%. So get the booster!
Our immune system is complex. The immune effect measured by anti body production is only one part of the protective effect. It can be hypothesized that boosting the cellular immune response, which is not generally measured, can offer more robust protection.
Dr. Neuman: Several studies agree that between 1/10 and 1/80th of your neutralizing antibodies will still work against Omicron and gives you better protection so boosters are a good idea! A recent study reports that Omicron is about 6 1/2 times more likely to reinfect, compared to Delta.
Do we need fourth and fifth boosters every 6 months?
Dr. Neuman: Based on current data, it appears boosters are necessary until we get to some level of immunity that could last for a reasonable length of time.
Dr. Fan: In Israel, results of a study measuring resurgence of antibody levels after four shots, showed they were not as impressive as after the third shot. Its ability to curtail the infection rate was not as robust. What’s unknown is whether the timing of the booster after six, twelve months, or later, can prove more effective.
What does fully vaccinated really mean?
Dr. Neuman: The immune system does not get full, so boosters are the best idea that we have against the virus. These additional doses of the vaccine raise cellular immunity and antibody immunity, giving broader protection.
If you test positive, the science says you can come out of isolation only when you test negative, not before. Anything other than that is only going to make more COVID.
Dr. Fan: Remember that protective effects are graded. Unvaccinated people are the least protected. The more shots you get boosts the immune system. Whether that translates into protection against hospitalizations, death or infection, needs to be vetted more thoroughly. More data is needed to give a graded rating of people who are vaccinated.
Can levels of antibodies in your system predict who is vulnerable to Covid?
Dr. Neuman: There’s a lot of randomness built into the process of predicting how many antibodies are needed for protection. The best mathematical models now can only predict with about 85% accuracy that if you have a certain amount of a certain type of antibody, you can expect protection. At the moment there is no point at which we can say you are 100% protected.
Dr. Fan: I would caution against using antibodies alone to make a call on protection level. The immune system is complex. Measurement of antibodies is a very small aspect of the immune system. There are no good co-relating studies which prove that if you have a certain level of antibodies you have a specific level of protection. It is not true that the more antibodies you have the more you are protected. Too many antibodies can over-activate the immune system which explains the side effects after vaccination. The peaks and valleys of the antibody level, the timing of boosting it, the kind of antibodies, in addition to cellular and other immune protective responses, are all part of the same picture.
Can we predict predominant variants in in the US
Dr. Fan: Because you can’t survey every infection, but viral titer just a sample, this spot-check only provides a ratio of how many variants are Alpha, Delta, or Omicron, not which variant is predominant in different regions of the country.
Dr. Neuman: We generally sequence whole genomes but the spikes are different enough between Omicron and Delta that you can reasonably estimate using a ‘spike drop out test’ to predict what virus is present.
Are new variants in the pipeline?
Dr. Neuman: It is inevitable. As long as the virus grows it will evolve into variants that move beyond the reach of some parts of our immunity. At some point, at a practical level, that’s a new variant. There is a lot of virus growing in America at the moment.
Are schools safe to open?
Dr. Fan: Yes. With infectious disease as with any other field, you balance the risk and benefit. Right now, the benefits of opening society outweighs the benefits of shutdown. My concern is not about vaccination, but about the side effects of a shutdown society and its aftermath.
Dr. Neuman: As a virologist I would say that we should not do anything that leads to more virus. From that perspective schools could open if masking or vaccinations are in place.
Can society open safely?
Dr. Fan: What we do know is that boosted, vaccinated people are the best protection. Common sense measures like masking, social distancing and washing hands can safeguard against the virus. But it’s difficult to impose a uniform, nationwide mandate from a federal level for everybody; it needs to be tailored to local situation. We have to learn to live with COVD however brutal it is.
Dr. Neuman: Herd immunity is elusive for this particular virus. In America the level of infections and vaccination should put us at the threshold for herd immunity, if this was a viable concept for SARS COVI2. Thinking in terms of an immunity window is more useful. A window may only last as long as a booster or an immune response is effective, which is 6 months to a year. By dropping all Covid restrictions to slow the spread of the highly transmissible Omicron, as the UK has done, you potentially buy yourself a 6 month respite but you almost also guarantee yourself a much larger problem in another 6 months.
Possibilities of Covid19 becoming endemic, like the flu.
Dr. Fan: Most variants of this virus just die, but some are viable. Look at the 1918 Spanish Flu – the previous well-known pandemic. We don’t have accurate data, but we can take a reasonable guess at how many generations of variants it created and how it eventually went away. I’m not convinced that the Spanish Flu vanished because everyone got vaccinated by 1920. I think there are other unknown factors that make a virus disappear. Perhaps the nature of the rise and fall of the virus plays a much bigger role than we understand.
Dr. Neuman: One of those is competition between viruses. As we understand evolution, what we call selective pressures (or what benefits the virus to keep going) can lead to a milder version of the virus. But I do not see that with this virus. The virus normally spreads the first week after infection. If a person is hospitalized, or dies, that happens 2 to 4 weeks later. I don’t trust the virus to change the way I would like it to change. In a given year the Flu will kill between 12 thousand to 16 thousand people, while Covid will kill several hundred thousand – so it’s a more serious problem
When people talk about the disease becoming endemic, they are talking about a shift in how to respond to Covid. I would argue that we should fight this thing, until we have exhausted every possible opportunity to get rid of COVID.
The reward for doing that is a world where you don’t worry about COVID and you don’t have to live with that number of deaths and hospitalizations in the ones you love, and that’s worth fighting for.
Meera Kymal is the Contributing Editor at India Currents and a 2021 grantee from the USC Center for Health Journalism, reporting on domestic violence in the South Asian community.
Photo by Daniel Lee on Unsplash