In the last few weeks, the COVID-19 Delta variant has all but taken over in the U.S. By mid-August, the U.S. had reached 36.9 million cases and 620,000 deaths.
What do we know about the Delta variant?
Highly contagious, the Delta variant is as contagious as chicken pox, the most contagious respiratory virus known to man.
Some data suggests that the Delta variant might cause more severe illness in unvaccinated persons than previous strains. In two different studies from Canada and Scotland, patients infected with the Delta variant were more likely to be hospitalized than patients infected with Alpha or original virus strains.
Unvaccinated people remain the greatest concern. Individuals infected with the Delta variant, including fully vaccinated people with symptomatic breakthrough infections, can transmit it to others. As of August, the CDC was still assessing whether fully vaccinated people with asymptomatic breakthrough infections can transmit. However, the greatest risk of transmission is among unvaccinated people, who are much more likely to contract and transmit the virus.
While fully vaccinated people with symptomatic Delta variant breakthrough infections can spread the virus to others, they appear to be infectious for a shorter time. Previous variants typically produced less virus in the body of infected fully vaccinated people (breakthrough infections) than in unvaccinated people. In contrast, the Delta variant seems to produce the same high amount of virus in both unvaccinated and fully vaccinated people. However, like other variants, the amount of virus produced by Delta breakthrough infections goes down faster in fully vaccinated people than in unvaccinated people.
COVID-19 variants of interest
Over time more variants will appear through mutations of the virus. The World Health Organization Weekly Epidemiological update for June 22, 2021, described seven variants of interest: Epsilon, Zeta, Eta, Theta, Iota, Kappa and Lambda.
How variants arise
The virus that causes COVID-19 is composed of four main structural proteins: spike, envelope glycoprotein, nucleocapsid and membrane protein. Mutations in the spike proteins cause variant change. The surface spike glycoprotein cleaves into two parts: one that facilitates incorporation of the virus into the host cell and another that is responsible for virus-cell membrane fusion.
How dangerous is COVID-19?
A comprehensive systematic review and meta-analysis involving 212 studies comprised of 281,461 individuals from 11 countries or regions noted that about 23% of COVID-19 infected patients have severe disease with a 6% mortality rate.
Another large meta-analysis of COVID-19 reported laboratory abnormalities in 8,697 patients that included lymphopenia (47.6%), elevated C-reactive protein levels (65.9%), elevated cardiac enzymes (49.4%), and abnormal liver function tests (26.4%), as well as other laboratory abnormalities.
Over 50% of COVID-19 patients have cardiac infection, and 20% have active clotting. Compared to the handful of vaccinated patients who developed these problems, unvaccinated people are clearly at a much higher risk.
What can we do?
We don’t know for sure when this pandemic will end, but we can continue to fight it with a multi-pronged approach:
- Masks, face shields and handwashing protect you and those around you even if you are vaccinated.
- Social distancing remains a cornerstone of prevention.
- The more of us who are vaccinated, the better off we will be. In many countries, less than 2% of the population has been vaccinated, creating fertile ground for variants to develop.
- Antiviral drug treatments may be our best chance to get back to normal. This approach targets the virus’s replication mechanism to stop it dead. We have some antivirals in our arsenal, and more are on the way.
- Immune antibodies, like convalescent plasma and manufactured antibodies, can be valuable to those fighting the disease.
- Immune stimulants rev-up our own defenses to attack and kill the virus. These include interferons, interleukins, cytokines and antibodies to cytokine receptors. Gene-directed therapies, like Janus kinase inhibitors and Bruton’s tyrosine kinase, are currently being evaluated.
- Seek early diagnosis and intervention to save your life and the lives of others around you.