Variant viruses are essentially mutated versions of the original form of a virus, in this case the SARS-Cov-2 coronavirus which causes Covid-19. This virus mutates all the time, as do all viruses. Most mutations are harmless and do not change the behavior of a virus to any significant degree. Some mutations may even cause it to die off but some cause it to become more aggressive and resistant to treatment, as has occurred with the Delta variant of SARS-Cov-2.
Variants are categorized as “variants of concern (VOC)” and “variants of interest (VOI)”.
Variants of concern have the following characteristics:
- Increased receptor binding affinity because of spike protein mutation.
- They are not as well neutralized by the circulating antibodies from previous infection and/or one of the available vaccines.
- Available treatments are not as effective.
- They may elude diagnostic tests.
- They result in increased severity of disease.
- Are more infectious.
Variants of interest are similar to variants of concern but have:
- No evidence for reduced treatment efficacy.
- No evidence of increased ability to avoid antibody detection.
- Limited prevalence.
- Limited or no change in infectiousness.
The present Delta variant ravaging the country, and most of the rest of the world, is a VOC, however, it is still identifiable readily with testing. Delta “Plus” is very similar to Delta with one additional mutation but its behavior is essentially the same.
The newest player is Lambda. Although it is technically categorized as a VOI, that will likely change.
It first showed up in Peru last August (2020) but very quickly spread all over S. America. And then it spread around the world and is now in over 30 countries with nearly 1000 cases identified in the US as of June, 2021. Were it not for the more well established Delta variant, it would undoubtedly be the predominant strain around the world. The WHO has classified it as a VOI however.
In Peru, it has led to a fairly high mortality at 9% but that number has not panned out yet in the US and areas outside of S. America.
Lambda’s spike protein mutation is different from Delta’s mutation. It involves an area of the spike protein known as a “super site” since it occurs in an area targeted by newer monoclonal antibody treatments, potentially making them less effective in treating severe infections. In addition, antibodies from patients who have received the Sinovac (Chinese) vaccine, the predominant one in S. America, have been less effective against the Lambda variant.
Both of these issues make this variant potentially significantly more infectious and less treatable.
Is it more lethal or cause more disease? Whether it is truly worse or simply a matter of an overwhelmed and less efficient medical system in countries like Peru, is unclear yet. Also, most people in Peru lack healthcare so they may simply be presenting much later in their disease.
At least in the lab, it appears that Lambda has more infectivity. In addition, it seems that Lambda also binds with greater affinity to the ACE-2 receptor. As far as antibody neutralization of the Lambda, also in the lab, it seems to still be pretty good.
Lab testing of the Regeneron antibody cocktail is still very effective at neutralizing the Lambda variant as well.
In a nutshell, Lambda seems to be very similar to the Delta variant in terms of it’s increased adherence to the ACE-2 receptors and may cause more infections; however, we have not seen that YET in the US. Stay tuned
The bottom line is that VACCINATION provides protection to all forms of this disease and it is imperative that everyone get vaccinated.
Also, following all those other protective measures is imperative.
MASK UP
DISTANCE
WASH YOUR HANDS
VENTILATE
GET HEALTHY!
Stay safe and be well.
AC