The highly infectious Delta variant is driving a COVID-19 surge, especially in some of the least-vaccinated areas of the U.S. We sat down with Verily Head of Clinical  Strategy and Policy Rob Califf to understand what to expect and the outlook for returning to school and work this fall.

Many employers are mandating vaccination to return to the office. How should you think about your COVID risk based on vaccination rates at your workplace?

The pandemic is a rapidly changing situation, and the Delta variant has many employers re-assessing their plans for returning to the office. The finding that vaccinated people who get infected can transmit the virus has important implications.

There are different categories of workplaces. More employers are requiring vaccination, and this is legally upheld by the Equal Employment Opportunity Commission and the Justice Department, with the rationale that not getting vaccinated poses a risk to one’s self and to others in the workplace. If you’re in a workplace where everyone is vaccinated, your risk is lower. Especially if that workplace is not heavily crowded, going to work under those circumstances would be considered low risk. If there is no vaccine mandate, and there are unvaccinated people in your workplace, it is wise to mask and maintain social distancing.

We started with a six foot rule for social distancing to avoid infection, but I think it’s also important to note that when it comes to COVID-19 transmission, risk actually exists on a spectrum. Being alone outdoors is probably the lowest risk, while crowded bars are significantly higher risk, and every situation in between depends on multiple factors. Public health experts recommend considering the local infection rate where you live, and increase masking and social distancing based on this estimated local rate of spread and other factors like how crowded the space may be and what type of ventilation is in place.

Employers and universities need to think about these things as well, and factor in variables like the size of their employee or student population, total vaccination rates, and frequency of testing. Because making these calls can be a challenge without a deep clinical background, there are tools available to help employers and schools make informed decisions tailored to their unique circumstances based on data science.

The CDC has recommended universal indoor masking for the upcoming school year in K-12 schools. Many universities are also requiring indoor masking and vaccination to return to campus. If the vaccination rates for young people improve and there is high enough uptake of vaccines for children once available, could this guidance potentially change?

Enforcement of the CDC’s recommendations for masking in K-12 schools is up to local health departments, so there will likely be variation. Colleges and universities are also setting individual policies for on-campus masking. What we do know is that safe in-person learning is possible with masking and moderated social distancing. At the start of the pandemic, there was much more concern with cleaning surfaces, which we now know is really not a significant factor in how the virus spreads. This is a respiratory virus, and ventilation is much more important.

Vaccine clinical trials for children under 12 are happening now, and hopefully the data will look as strong as they have been for adults. When children can get vaccinated, there is a good chance it may deescalate mandates for masking and social distancing in K-12 as long as a new variant doesn’t come along that has worse effects on kids. While kids are still low-risk compared to adults, we are seeing that the Delta variant is affecting children more seriously than other variants did. Unfortunately, especially in high-spread low-vaccinated areas of the country, we’re seeing greater numbers of children hospitalized with COVID-19. Right now, the best thing adults can do to protect the vulnerable children in their communities is to get vaccinated themselves.

The Delta variant is significantly more infectious than the original COVID strains, though “breakthrough” cases in vaccinated people are considered rare based on current data. What is accounting for the rapid spread of Delta, even in highly vaccinated states? 

The Delta variant is so infectious that it finds unvaccinated people easily. A report in June found Delta was spreading 50% faster than the previous Alpha strain, which was 50% more contagious than the original strain of the virus. By the end of July Delta was causing 80% of U.S. COVID-19 cases. One study also found that viral load, or amount of virus in the body, caused by Delta is roughly 1,000 times higher than the viral load in people infected with the original strain. This is another factor in how Delta can spread quickly.

If you’re in a place with a high rate of transmission, a higher percentage of those cases will be in unvaccinated people. We do know that the vaccines are still very effective at preventing severe disease and death. The risk of symptomatic disease is actually reduced eightfold by getting vaccinated, according to data from the CDC. The more people get vaccinated, the better our chance of stopping the pandemic.

Data from Pfizer shows vaccine efficacy goes from around 96% to 84% six months after receiving the vaccine. How likely do you think it will be that additional doses are needed? 

This is evolving, but the FDA recently authorized a third dose of the Pfizer and Moderna vaccines for high risk immunocompromised people. The White House has also announced that third doses of the Pfizer and Moderna vaccines will be available to all vaccinated individuals eight months out from their second dose starting in September. More data is required to authorize a booster for the Johnson & Johnson vaccine.

Additionally, the fact that mRNA vaccines were created through a generalized platform means that they can be updated for variants now in play. While we’re still learning and gathering data to understand the exact frequency of vaccine doses we’ll need going forward, we don’t expect a yearly vaccination like the flu shot will be needed.

How are we doing in the U.S. with testing and monitoring COVID now?

Testing is much more available in the U.S. now, and going into the fall and winter, we still need to develop more of a strategy to define how often people should be tested based on whether or not they’re vaccinated. During cold and flu season especially, it will be important to know quickly whether or not an illness is COVID. Another area that we expect to see more of is wastewater testing to understand community spread. With COVID, you’re infected for a few days before you turn symptomatic. Wastewater testing can help us see spikes of COVID before people get sick and potentially cut off an outbreak before it gets serious.

At this point, a lot of people have been infected with Delta. How will that affect the overall immunity of the population?

Very broadly speaking, people developing antibodies to infection does reduce risk in the population to some degree. But that said, before Delta, having a previous infection did not give you as much immunity as getting vaccinated. Getting the vaccine provides a different type of immunity and it’s strongly recommended people get vaccinated, even after a previous infection.

Switching gears a bit here. Some people are holding out on getting the vaccines authorized in the U.S. pending full approval by the FDA. What is the difference between an Emergency Use Authorization (EUA) and full approval? 

It’s critical to recognize that the E in EUA does not mean experimental, it means emergency. When there is a true national emergency, declared by the federal government, the FDA has the authority to use all available data to understand the risks and benefits of a health intervention like a drug, medical device, or vaccine. An Emergency Use Authorization means that the FDA, during an ongoing state of emergency, has evaluated the vaccine and decided the benefits outweigh the risks. When it comes to the vaccines approved in the U.S., data show results as strong as, if not stronger than, any vaccination effort in history. If you get the vaccine, you are less likely to be dead, hospitalized, or have long-term symptoms.

So why doesn’t the FDA just give full approval? Full approval of a health intervention includes many other things beyond the safety and efficacy data, like marketing and advertising, supply chain analysis, manufacturing plan inspections, and many other details. The Pfizer vaccine was fully approved by the FDA on Aug. 23 and we expect the other authorized vaccines to follow in the coming weeks, but waiting on that isn’t smart in the face of overwhelming data.

How concerned should we be about variants other than Delta, such as the Lambda variant has been detected?

We don’t know enough about Lambda to tell what effect it may have. Variants that become predominant don’t necessarily always make people sicker. That said, the more unvaccinated people there are domestically and globally, the higher the risk that more dangerous forms of COVID will emerge.

Learn more about Verily’s efforts to fight COVID-19, including Healthy at Work for employers and universities, the Baseline COVID-19 Testing Program, and the Baseline COVID-19 Research Project at