The Delta variant is becoming a dominant COVID-19 strain worldwide, and is increasing rapidly in the United States. We sat down with immunologist Dr. Charlie Kim, Head of Molecular Sciences at Verily, to learn more about it and the threat it poses to vaccinated and unvaccinated individuals.

What makes the Delta variant so dangerous?

The evolution of the new coronavirus that causes COVID-19 is to be expected, but of course it causes new challenges. What we're seeing now is an example: because of the difficulty of getting vaccines into arms quickly globally and expanding access to testing, it's forced an evolution of more severe forms.

What's concerning about Delta is that it's more easily transmitted, and it's spreading to different parts of the world quickly. Based on early data, it also causes more severe health outcomes. Vaccines do offer protection, but not all vaccines are as protective against Delta as they are against the original strain of the virus. We need to keep the pressure on vaccination, and in areas with low vaccination rates, testing, masking and distancing.

What threat does it pose to vaccinated people? Unvaccinated people?

Vaccination is still worthwhile. You should be vaccinated if you want protection against any variant, and vaccination still provides strong protection against severe outcomes like hospitalization and death. Fully vaccinated people are more protected against Delta than those who have only received one shot.

What we're seeing is that in communities where there's a lot of infection with Delta, even vaccinated people are more likely to get infected than they were with previous strains. If you're not vaccinated, you're definitely at greater risk than you were a year ago with Delta.

If you previously recovered from COVID-19, you likely have some natural immunity, but the recommendation is still to get vaccinated because it offers a different level of protection.

Where does this leave people with children under 12 and those who cannot get vaccinated for medical reasons?

Children under 12 are considered unvaccinated individuals, so the CDC's guidance is to follow guidelines for unvaccinated people including masking. The same applies to immunocompromised individuals who are not able to get the vaccine.

That said, the more adults who are able to get vaccinated do so, the better. This can bring down the overall infection rates and make things much safer for children and immunocompromised adults.

How does relative risk change based on vaccination rates in your area?

There is a lot of variation in vaccination across the United States. In San Francisco for instance, around 70% of eligible people are vaccinated. Other areas have much lower vaccination rates. Generally, the higher the rate of vaccination in an area, the safer it is. In areas where vaccination is on the low side and there are still infections, it makes sense to continue to be cautious. That said, we live in a global community and we've seen that as long as the virus is continuing to spread unchecked in one area of the world, it does create risk for all.

What would you say about those who are hesitant to get vaccinated due to possible side effects?

The vaccines authorized in the U.S. are first-in-class vaccines with a truly remarkable track record in efficacy and safety. We now have data from hundreds of millions of people, and it is remarkable how well the vaccines are working and how safe they are. While there have been some cases of side effects, the numbers are very low, the incidents have been investigated by regulators, and it's been determined that the risk of complications from COVID-19 are much higher than any risk from the vaccines.

The vaccines, particularly the mRNA vaccines from Pfizer and Moderna, are working well for now. What is the end game if the virus mutates to become fully vaccine resistant?

Let's start with an example for comparison here. The flu virus evolves very quickly, and it's a constant struggle every year to keep up with vaccines. Coronaviruses usually evolve more slowly. Right now, the reason why we're seeing quicker evolution is because it is so widespread.

If we can create enough immunity in the global population and reduce the number of infections, that will decrease its ability to evolve quickly, which means fewer severe variants. That is, if we can be aggressive about vaccinations in the U.S. and worldwide.

What do you think the future priority research areas are for COVID-19?

At the start of the pandemic, around 10-20% of Americans in the hospital were dying, which is a huge number. In late 2020 to early 2021, an evolution in care pushed that down to around five percent. Part of that was new medical treatments, and part of it was changes in care. For example, we found that a process called pronation, or rolling a person on their side to oxygenate their blood, was effective. Going forward, I expect to see more research done in the area of treatments.

To learn more about the Baseline COVID-19 Research Project and how you can get involved, visit our website.