Riding the Delta wave

Is this how we get to "herd immunity"?

It’s been awhile.

My last post was 2 months ago. At that time, I was feeling pretty good. Cases were dropping, hospitalizations were dropping. My father came and went for a visit. There were distant rumblings about some variant out in India that was causing a lot of disease, but it was far away in a land without a lot of vaccine.

That variant B.1.617.2 , renamed Delta (sorry, Delta Air Lines), has now become the dominant variant in the United States, with breathtaking speed. And for good reason—Delta has 1000 times more infectious viral particles in the noses of infected individuals than the original strains of SARS-CoV-2 (COVID-19), and period of infectiousness is much earlier than with the original strain. Researchers in Guangdong, China started tracking Delta in May, 2021, and found that peak infectiousness shifted from 7 days to 3 days.

This adds up to a potent variant that will spread more widely and quickly than other strains. That’s the bad news.

The almost unbelievably great news is that the vaccines distributed in the USA from Pfizer/BioNTech, Moderna and Johnson & Johnson are still highly protective against severe disease. About 99% of recent deaths, including from Delta variant, are in people who are not fully immunized.

So what does this mean if you are immunized? It means you are more likely to catch COVID-19 from the Delta variant, especially if you live amongst many unimmunized individuals, than you were from the previous variants. However, you are still protected from the most serious consequences (hospitalization/death). Unfortunately, immunized people may be more likely to transmit Delta than previous variants—theoretically. In a previous post, I asked, “What do people really want?” from their vaccines. This was before the CDC said unvaccinated people no longer needed to mask in most situations. (We still require masks in the healthcare setting where I work—the consequences of transmission to our vulnerable patients is just too high.) The best reason to get vaccinated is to not die. The next best reason to get vaccinated is that it may reduce your risk of passing disease to others.

For people who are not vaccinated, and never infected, the chances of catching COVID-19 have gone way up. It is known that about 10% of the US has tested positive, and highly likely that many more (probably more than 20%) have been infected but not tested. Almost 50% of all Americans are fully vaccinated. While it is likely there is quite a bit of overlap between immunized and previously infected people, the rise of cases in the USA over the last few weeks suggests we are not yet at “herd immunity”.

So how does this end? SARS-CoV-2 has shown itself to be a wily foe—able to mutate into more transmissible forms. However, to date, it has not mutated into a significantly more lethal form, nor able to significantly pierce immunity provided by vaccines. While there was concern that the variant first seen in Brazil, formerly P-1, now called Gamma, could get past the immune system in people who recovered from previous infection from COVID-19, the vaccines still seem to be effective against that strain as well.

My expectation is that we have now entered a hybrid experiment—a combination of the unfettered transmission proposed by the Great Barrington Declaration folks, and the powerful protection against severe disease from the vaccines—possibly with boosters in the near future, especially for immunocompromised people. Most at risk in this experiment is children, for whom no vaccine has been approved and we know can catch and transmit disease, and those adults in their lives, especially those who are immunocompromised. Those communities will still need to mask, test and receive monoclonal antibodies as soon as they know they are infected.

I expect that by summer of 2022, most will have either been immunized or infected, and that COVID-19 will continue to circulate in low numbers in the community. I don’t expect shutdowns again, nor will most places put in mask mandates. However, those who are immunocompromised, or live with people who are immunocompromised, may want to hunker down for the next few months, mask up when in public, and have a strategy to get tested should they be exposed or have symptoms of COVID-19.

For those of a certain age, who remember Hill Street Blues—