Like fire racing through a field of dry grass, the COVID-19 coronavirus has raced through the country and world over the last year in record numbers. With more than 137.5 million cases globally and 31.3 million of those in the United States to date, there have been plenty of opportunities for the virus to evolve and for different variants or types of the virus to form.
A variant is a virus that is genetically and biologically different from the original form. According to Dr. Philip Fracica, chief medical officer at Bothwell Regional Health Center, variants occur due to spontaneous mutations that are “errors” in the copying of the virus’s genetic material. The majority of the errors result in a new changed virus that is less capable of infection and spread; however, there are sometimes “lucky” changes that occur that make the virus more successful in spreading through populations.
“Every infected person has billions of virus particles at any one time and those particles are continually reproducing during a period of a couple of weeks,” Fracica said. “The result is that there is an incredibly large number of virus particles actively reproducing. The spontaneous emergence of a new variant that can spread faster than prior forms of the virus is sort of like the odds of winning the big jackpot if you buy a few hundred billion lottery tickets. Even very rare outcomes will occur if given a sufficiently large number of tries.”
Fracica shared that these jackpot mutations are the ones to care about as they enable the virus to spread faster or evade immune defenses.
“What starts as a mutation in a few viral particles will eventually catch up with and replace the original form of the virus,” he said. “Those new strains are replaced as additional spontaneous changes occur. It’s actually a pretty fascinating process of viral ‘evolution’ that we are watching as it occurs.”
The U.S. Centers for Disease Control and Prevention (CDC) is monitoring five “variants of concern” defining them as ones "for which there is evidence of an increase in transmissibility, more severe disease (increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures."
According to the CDC, the B.1.1.7, or United Kingdom (U.K.) variant, is the most common variant circulating in the United States and has been reported in all 50 states, the District of Columbia and Puerto Rico. In Missouri, the U.K. variant was first reported in February. The latest cases have shown up in Jackson and Boone counties. Based on currently available data from the CDC from early March, an estimated 27.2% of COVID-19 cases in the United States are caused by the B.1.1.7 variant, which is about 50% more transmissible than the original virus.
“There are many thousands of genetic variants, but those on the CDC’s watchlist are the most serious right now,” Fracica said. “So far there have been no new strains identified that are more deadly in the sense that infected individuals would have a greater risk of death or severe illness, but most of the variants spread more easily and are more infectious.”
Fracica said the “spike protein” is what the virus uses to attach to and infect body cells and also the part of the virus that antibodies target to defeat the virus by blocking cell infection. Changes in the spike protein are the key to what makes the variants behave differently. Not only do we need to worry about spike protein mutations that promote greater infectivity but the new forms of spike protein may be sufficiently different from the original protein that protective antibodies directed against the original form cannot neutralize the new virus as well as the original form.
“A good analogy is to think of the antibody (from an infection or a vaccine) as a custom-tailored garment designed to fit exactly to a person’s size and body shape,” he said. “In the case of the virus, the antibodies have been ‘custom fit’ to the original spike protein structure. The more the spike protein changes, as happens with the variants, the less well those initial antibodies will “fit” and neutralize the virus.”
While the U.K. variant isn’t more deadly than the original virus, it has spike protein changes that result in both an increased ease in transmission and diminished protection from antibodies. It is this “double threat” nature of this variant that has medical scientists particularly concerned.
On April 9, the CDC reported the United States is in the fourth week of an upward trend in COVID-19 cases. Experts say the uptick could be from restrictions that have been relaxed or lifted or due to the more contagious virus variants. In Pettis County, the positivity rate, which is the percentage of people who test positive for the virus of those overall who have been tested, has moved from 1.76% in the last week of March to 4.54% for the week of April 8. Fracica said the upward trend indicates it’s still important to be vigilant about precautions like social distancing and mask use and to get vaccinated for the COVID-19 virus to continue to protect everyone in the community.
“We definitely know that most variants seem to spread more easily and that the amount of exposure needed to get infected is significantly lower,” he said. “For example, it might be necessary to stand within six feet of someone not wearing a mask for 10 to 20 minutes to become infected with the original virus while one to two minutes of exposure might be enough for a variant.”
While no variants have been reported in Pettis County yet, Fracica said it’s likely just a matter of time before one or more appears and that vaccination is still useful protection.
“Even if the variant is less susceptible to neutralization by antibodies customized to the original virus, there is still likely to be significant protection from a vaccine, which is better than nothing,” he said. “The emergence of variant strains make social distancing and mask use more important than ever for individuals who are not immune. It also means that people who have been previously infected or who have been fully vaccinated are unfortunately still at some risk of illness if exposed to a variant strain.”
Fracica shared his biggest worry is that there are no signs that the virus has stopped changing, and he’s concerned about what would happen if there’s an even greater worsening of infectivity and resistance.
“It is not out of the realm of the possibility that we could see the emergence of a variant that spreads much more quickly and is totally unaffected by hard-won immunity from surviving an infection or having been vaccinated,” he said. “If this ‘nightmare’ scenario were to occur, we could essentially find ourselves back at square one with the global population defenseless but now with a new ‘super’ form of the virus spreading through the population much more quickly.
“The best way to keep that from happening is to reduce the total number of global infected cases as quickly as possible because the emergence of new variants is directly related to how many active viral particles are actively reproducing. It is appropriate to describe this as a ‘race’ with the variants because if we can reduce the global burden of infection we can cripple the ability of the virus to develop new variants. If we cannot significantly reduce the number of actively infected humans, the high rate of development of new variants is likely to continue with the potential for serious consequences.”
Fracica said getting vaccinated as well as continued use of masks and social distancing is the best way to keep infection rates low in the community.
“That is the best way to not only help preserve the health of our neighbors but also to ensure that the infection does not compromise the economic prosperity of the community and ensure that business can function at full capacity.”