What’s Up Doc column: How much more infectious are the new variants of COVID?
Columns share an author’s personal perspective.
Q: What does the emergence of the new COVID variants really mean?
A: The short answer is that we must double our vigilance to avoid yet another rebound of increasing numbers of people becoming infected, hospitals being overwhelmed and yet more avoidable deaths.
Upon viral replication, the genetic material, RNA for the RNA viruses including SAR-CoV-2 or DNA for DNA viruses, can mutate. The more people infected with a virus, the bigger the chance that these somewhat random mutations will occur.
Most viral mutations do not make a significant difference in the virus’ functionality. Some mutations may actually make the virus nonviable. But some mutations may make the virus more infectious, more deadly or cause other clinically significant changes. The more infectious viral variants have a survival benefit as their increased infectivity causes more people to be infected by them and subsequently pass them on to others. Therefore, more infectious variants are more likely to spread.
A variant is a slight change in an established virus, typically due to a small(ish) number of mutations. A new strain of a virus implies a pretty distinct new version of it which causes a significantly different immune response and has a larger difference in how it functions (for example, in how it enters a cell and/or then usurps the cell’s functionality to multiply). The CDC is partnering with multiple commercial laboratories to surveil for possible new emerging variants, evaluating thousands of samples every week.
Since the pandemic started, there have been many thousands of mutations of the SAR-CoV-2 virus. We are still learning more about the new emerging SAR-CoV-2 variants including the B.1.1.7 variant first identified in the U.K., the B.1.351 variant first identified in South Africa, the P.1 variant first identified in Brazil, and many others - including some first identified in the U.S. - all of which have already infected some people in the United States.
How much more infectious are they? Do they cause more severe disease, or even different symptoms and complications? Will the vaccines work to prevent severe infections from them, and if so, which vaccines will remain efficacious? Here is a summary of what we know now:
• Some of these new variants appear to be more infectious (as discussed above, this is not surprising). For example, in November, about 25% of cases in London were from the B.1.1.7 variant, but by mid-December it was 67% of cases.
• Symptoms caused by some of the variants are different. For example, loss of taste/smell seems to be less common for some of the emerging variants.
• Certain tests for COVID may be less sensitive in some variants. The specifics of this are still being evaluated.
• At least some of the new variants are at least slightly more deadly. For example, the B.1.1.7 variant seems to have increased mortality in males aged 55 to 69, from 0.56% to 0.73%.
• People who have had COVID develop antibodies. In addition, some pharmaceutical companies have developed antibodies that can be used as treatments for people who are infected to prevent them from developing serious symptoms such as getting sick enough to require hospitalization. The efficacy of these antibodies may be compromised to some extent for some of the emergent variants. This is also being actively evaluated.
• Similarly, vaccinations stimulate development of neutralizing antibodies in people to help protect them. It is unclear whether and how much the mutations in these new emerging variants will compromise the efficacy of the vaccines being rolled out, but there is clearly some significant compromise in at least some vaccines’ efficacy. For example, South Africa has suspended the rollout of the AstraZeneca vaccine as the new variant endemic there showed less than a 25% response to it.
The emergence of these new variants may delay our march back to normalcy, which depends on our achieving herd immunity. In the future, we may all need booster vaccine shots to enhance our immunity to cover new variants (similar to the need for a new flu shot every year). There may also be some benefit of getting different vaccinations in combination.
All this is yet another reason that a worldwide pandemic MUST be addressed throughout the world, and a U.S.-only approach is destined to fail. For now, we must all continue to follow practices to prevent person-to-person transmission of COVID, including wearing masks, social distancing, and hand washing. And please, when it is your turn, get vaccinated; even if the vaccine is not as effective against some of the variants, it is THE huge step we need to help put this pandemic behind us.
Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com.