Dear Dr. Eva, 

We are hearing about another new Covid variant, Delta. We’ve already heard about, and some people have panicked over, the British variant and the Brazilian variant. However, those don’t seem to have changed the course of the pandemic in our country. Is this just another cry of “wolf,” or is it really time to go get the masks out again?



Dear Skeptic,

It does seem as if there’s a new coronavirus scare every month. So far, new strains haven’t affected most people’s lives or the Covid death rate in this country as a whole. Unless you are following Covid news closely, the changes in recommendations don’t seem to make sense. The most famous example was early in the pandemic, when Dr. Fauci did not recommend the use of masks, and then later he did recommend using masks. Remember that? Most news outlets didn’t point out that health recommendations change because the situation changes.  The “no masks yet” recommendation was early in the U.S. Covid pandemic. As the virus spread and the Covid death rate increased, masks were needed.

Many of us have good protection from Covid because we are immunized. The 2/3 of the adult US population who have gotten the Covid vaccine are protected. Vaccinated people very rarely get sick from Covid and almost never die of it. The vaccines used in the U.S. are almost as effective in preventing illness from the Delta variant and other Covid strains as they are in preventing illness from the original strain.  Unfortunately, some other vaccines, including the Chinese vaccines Sinovac and Sinopharm and the Russian vaccine Sputnik V have turned out to be much less effective.

So, why the latest recommendation that everybody, including vaccinated people, put our masks back on? Only to protect the unvaccinated people? What if I am happier without my mask and don’t care about protecting people who haven’t bothered to protect themselves by getting vaccinated?

That’s not all there is to it. The more people that are infected, the more viral reproduction (copying) occurs. The Covid virus doesn’t replicate itself perfectly, so many mutations occur, which causes the development of new strains. Some of the variants are less dangerous than the original strain, but others are much more dangerous.

Why Delta is more dangerous

The delta variant, which was first identified in India in October 2020, has become the dominant strain in Great Britain, where it now causes more than 90% of new Covid cases. In the U.S., the delta variant accounts for more than a third of new cases, and that number is increasing quickly.

Delta is both more infectious and more deadly. The hospitalization rate of people infected with Delta virus is twice that of people infected with earlier strains. The death rate is also higher. In addition, the Delta virus is causing serious illness in more young people in their 20s and 30s who do not have any underlying health problems.

Delta’s mutations make it easier for the spikes of the virus to attach to human cells. This means it can infect people faster and copy itself faster. Because of this, a person infected with the delta strain is likely to infect seven other people. With the original strain of Covid, an infected person typically infected two other people.

Delta’s greater infectiousness also means that herd immunity will be harder to reach. To reach herd immunity against delta, which means the community  as a whole would be protected against infection, 83% of the population would have to be immune, either from vaccination or from infection. With the original strain, an immunity rate of 60% would have been enough to reach herd immunity.

Obviously, unvaccinated people should be wearing masks to avoid becoming seriously ill with Covid. But what if you have had the vaccine?         

Why vaccinated people should consider wearing masks:

  1. Even though they won’t get sick from Covid, vaccinated people can be carriers of the Covid virus, and they can transmit it to others.
  2. When they are carriers, unvaccinated people contribute to ongoing replication of Covid virus and development of more variants. One of the new variants may be resistant to the vaccine, meaning that all vaccinated people would be vulnerable.
  3. Some people’s immune responses are weak. They do not have a strong response to vaccinations, so even though they have been vaccinated they are not immune. This includes between five and 15% of people who have had any type of vaccine. There is no test available to find out who responded to the vaccine and is immune, and who did not respond and is not immune. So, there is a chance that, even though you were vaccinated, you are vulnerable.

Those are the reasons why masks are recommended again. You don’t like it, and I don’t like it either. I am a lot happier without a mask. The only solution in the long run is to get as much of the world vaccinated as possible. Viruses know no boundaries. The delta variant originated in India because only 5% of people in India have been able to get Covid vaccine. New variants will keep appearing until most of the world’s population has been vaccinated. This can be done. Smallpox, once a killer and mutilator of people all over the world, has been eliminated. Measles has been eliminated in much of the world. We can get the world vaccinated. It will take some time, but it’s the only long-term solution.

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Dr. Eva Hersh, MD
Dr. Eva Hersh, MD
Eva Hersh is a family physician. Send your comments and questions to her by email at