Demystify Delta
The Delta variant (first identified in India) is making more headlines. Many of my patients and readers are wondering: am I still safe after I’ve been vaccinated? What about my unvaccinated kids? Are we headed for a fourth wave? When will we need booster shots? Should I get a booster NOW if I’ve had the J & J vaccine?
Let’s start with the basics. Over the last year and a half, the novel coronavirus has mutated thousands of times. When a virus mutates in such a way that gives it a competitive edge — where it can better survive in the nose of its host or replicate faster, for example — it infects more people.
Delta is one such mutation. It is circulating widely in the UK (75%), and, as expected, it’s now taking hold in the US, accounting for somewhere between 6-10% of COVID cases as of today. Delta is clearly more contagious than other variants, however, it’s not clear yet whether it causes more serious disease than the “regular” coronavirus. (Higher numbers of infections in unvaccinated people do not necessarily mean more serious disease. In fact, the higher apparent transmissibility may be informed by human behavior. For example, a younger population with mild symptoms may not stay home when feeling slightly “off.” For a wonderful and very scientific discussion of human factors, this FABULOUS podcast with virologists is worth a listen.)
Here’s the bad news: if you’re unvaccinated, you’re more likely to get COVID-19 and you’re at higher risk of silently spreading the virus to other people from this new, more contagious variant compared to the “original” coronavirus.
Here’s the GREAT news: the mRNA vaccines from Pfizer-BioNTech and Moderna work beautifully against the Delta variant. These vaccines produce robust B cell (antibody) and T cell responses that essentially take the risk of death and severe disease off the table (96% protection, same as against the Alpha strain which was previously referred to as the “UK” variant of B1.117) and dramatically reduce the risk of COVID-19 from all versions of coronavirus.
So what’s the big deal about Delta?
What’s new is that it looks like we need two doses of the Pfizer or Moderna vaccine to get optimal protection from Delta. A single shot of the mRNA vaccine seems only to offer 33% protection against this variant (as opposed to 80-85% protection with one shot and 95% from two shots against the “original” coronavirus). That second booster dose really drives up production of antibodies to protect us from even very mild disease.
What about the risk of Delta for people who’ve had the J & J vaccine?
The data on J & J versus Delta isn’t fully in yet, but let’s recall that the J & J shot has a very similar mechanism of action as the AstraZeneca (AZ) vaccine, and we’re learning a LOT about AZ’s wonderful real-world effectiveness against Delta. Just yesterday a large study of 31,621 healthcare workers in New Delhi revealed that the AZ vaccine provided protection in over 95% of vaccinated individuals. Among the vaccinated, 81% of people had had two doses and 18% had had only one dose. There were ZERO deaths after vaccination and only 0.28% (90 out of 31,621) of vaccinated people required hospitalization. These are extraordinary results, particularly since this study was undertaken in India during the surge of Delta.
Meanwhile we’re learning that getting an mRNA booster after a single dose of an adenovirus-vectored vaccine (like AZ and J & J) is safe and produces a robust immune response. We don’t yet have real-world effectiveness data, but it stands to reason that people would fare better if confronted by Delta with a second shot on board. Indeed this “mix and match” plan is already being adopted by many countries like Canada, France, and Finland.
The upshot on J & J?
For most of my patients who had the J & J shot, I’m recommending a single mRNA vaccine dose as a “top off.” The FDA has yet to issue specific guidelines and algorithms on this, but in the meantime there is so little downside of getting a single shot of mRNA that this is my current recommendation to my adult patients.
What about people who’ve recovered from COVID-19?
Some very well-done studies (like this one) suggest that people who have natural immunity don’t need to be vaccinated at all. It makes intuitive sense: we recover from COVID by mounting a robust-enough immune response to win the battle. However, people have widely varying immune responses to COVID-19. For example, young and asymptomatic people may not develop a strong immune response while people who fought off the disease longer and had more symptoms might have more durable immunity. Therefore, I’m recommending vaccination with a single booster shot of an mRNA vaccine to many of my COVID-recovered patients. Just as with J & J vaccine recipients, there are no specific guidelines here, but one dose (instead of two) is probably sufficient to fend off reinfection in people with natural immunity. More formal guidelines will come as the data evolves.
What about unvaccinated kids?
We already know that children are less likely to get severely ill from COVID-19 — whether it’s from the “original” coronavirus or from the variants. And again, most virologists think that the Delta variant is not any more serious than the regular coronavirus — that it’s just more contagious. What’s more, unvaccinated people are indirectly protected from COVID-19 as local case rates fall and as more people are vaccinated. That said, If you are bringing young kids to visit an older relative who is unvaccinated, do watch out for headache, fatigue, runny nose and sore throat symptoms as these have been found to be fairly typical.
Meanwhile, the CDC is looking into concerns about myocarditis (inflammation of the heart) following vaccination among kids and young adults. Stay tuned for more on this in the press tomorrow, and I’ll talk about it in my newsletter next week as well. The condition is very rare, but if you do notice a teen or young adult with recent vaccination history talking about chest discomfort, especially when lying down, it’s important to seek care.)
Will we have a fourth wave?
My crystal ball is still on back-order, but the people I trust most in public health, epidemiology, immunology, and medicine suspect that we will not have another surge. Moreover, it’s important to define what we mean by a “wave.” There’s a big difference between a surge of people with colds and an uptick in hospitalizations and deaths. Moving forward, it’s also important again to acknowledge that COVID isn't going away and that we can expect outbreaks. It’s up to us as a society to determine what level of disease and devastation from an infectious disease we’re willing to “tolerate” to allow a more normal existence. These are the existential questions that keep my brain humming along!
What are the upshots?
Get vaccinated. The vaccine saves lives, protects our communities, and prevents illness in our most vulnerable populations. If you’ve only had one shot, sign up for the second one! Look at it as your free pass to (empathetically and respectfully) move past the deluge of Delta headlines.
Gently encourage other people to get vaccinated. I’ve been the most successful in convincing vaccine-hesitant people to get the shot — from my patients to two grocery store clerks! — when I invite a gentle, non-judgmental dialogue and help point people to information they might need OR when I express enthusiasm for the benefits of vaccination for our safety, sanity, and community.
Breathe easy if you’ve been fully vaccinated. Know that your risk of COVID-19 isn’t zero (and never will be) and that we do see breakthrough infections (and more so for Delta), but that the risk is still tiny. And if you’re in the unlucky small percentage of people who do get COVID-19 after vaccination, you’d likely have something between a runny nose and a mild flu. Plus, this would also serve as a natural booster against future infections.
Recognize that fear is circulating a lot more than COVID-19 is right now. Fear of variants, fear of vaccine side effects, fear of not getting vaccinated, fear of breakthrough infections after vaccination, and fear about the future are consuming many people’s thoughts at the exact moment that we could be enjoying the benefits of widespread vaccination. (Many people already are, and the more we blanket the country with vaccines, the better off we all are together.)
To be clear: In no way am I trying to dismiss the normal, appropriate fear we’ve all experienced on some level during the pandemic. Nor am I anesthetized to the widespread devastation caused by COVID-19, particularly to our most vulnerable populations. In fact, the physical and emotional fallout from the pandemic is the very reason I’m drawing attention to the concept of relative risk.
As the threat of COVID-19 retreats for all of us — vaccinated or unvaccinated — it’s important that we recalibrate fear, put the risk of COVID-19 into perspective, and pay close attention to the data as it evolves. It’s also critical to read more than the headlines and evaluate the potential biases of anyone (including me!) who is reporting on the pandemic.
Putting data into context and fact-checking our fears can help soothe our anxiety. So can a weekend of sunshine, sleep, and savoring the moment. I hope you enjoy yours!
I will see you next week. Until then, be well.