What you should know about COVID-19 variants: An interview with Johns Hopkins epidemiologist William Checkley
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As countries race to vaccinate their populations, variants of the COVID-19 virus have popped up around the world. The virus continues to fight to survive, and it has evolved and mutated itself to increase chances of its transmissibility. Associate Professor Dr. William Checkley, a pulmonary and critical care physician who is an epidemiology and global health expert at Johns Hopkins University, spoke to Hola Cultura about the burgeoning COVID-19 variants and their impact on the vaccinated and unvaccinated.
The four notable variants in the U.S. include the alpha, beta, gamma and delta, which have made their debuts at various points in the pandemic — with the earliest being the Alpha, which was detected in December 2020.The Delta was first detected in March 2021, according to a report by the Centers for Disease Control and Prevention (CDC).
Among the variants, Delta has become the most common strain of the virus. As of the end of July, it accounted for about eight in every 10 new cases in the U.S., according to a report from Yale Medicine. Delta has been spreading 50% faster than the Alpha variant, which was 50% more contagious than the original strain of the virus.
Checkley says that the virus will continue to mutate as it infects more people. The more people that get vaccinated, he says, the fewer people will get infected, reducing the chances for the virus to continue to mutate.
He emphasizes the importance of continuing vaccination efforts and says that one of the biggest misconceptions of the vaccines is that they will not be able to stand up to the variants.
“Even in settings with different variants (whether it is the one we have been in the U.K., South Africa or India), the vaccine still affords significant protection to be able to prevent severe disease.”
Checkley says that as the virus infects new people, it builds and mutates its genetic blueprint inside infected people, allowing strains like the Delta variant to build a higher transmissibility rate.
“There’s always an opportunity for mutations to occur. A lot of these mutations are errors in coding, but eventually some of these errors that are brought into their genetic code may provide the virus with an additional advantage for transmissibility or disease severity,” Checkley says.
As COVID-19 variants continue to mutate from the original virus—“the wild type”—other various strains compete against the wild type and each other.
“If a new variant has an advantage over the wild type or other SARS-CoV-2 variants, then that variant becomes the most common virus to circulate in the population. A small change in the genetic code may provide an advantage for transmissibility, allowing it to spread more easily,” Checkley says.
Since viruses are constantly changing as they infect more people, genomic surveillance allows scientists to decode genes to learn more about the virus, Checkley says. Since November 2020, the CDC has done this by regularly receiving COVID-19 samples from state health departments for further evaluation. Since January, the CDC’s national COVID-19 surveillance system has bumped up to processing 750 samples a week. Additionally, the CDC has contracts with 29 U.S. universities to conduct genome surveillance, as well as contracts with diagnostic labs across the U.S. that examine 20,000 samples a week.
The CDC has made note of cases where those who are partially and fully vaccinated have contracted the Delta variant. As of July 22, there were 65,000 cases of COVID-19 among the 160 million people who were fully vaccinated, according to a report from UC Davis Health.
The UC Davis Health report states: “That’s 0.04% of vaccinated people reporting breakthrough cases. No vaccine is 100% effective. With the COVID-19 vaccines averaging about 90% efficacy, health experts expect about 10% of those vaccinated could be infected.”
“The vaccine was developed for the spike protein. If the spike protein changes too much, then the virus may actually lose its advantage to be able to bind to human cells easily,” says Checkley, indicating that not all mutations make the virus more virulent.
Although the virus infects populations without distinguishing racial or ethnic differences, socioeconomic drivers of disease lead to disparities such as disproportionate fatalities among more marginalized groups, including Latino and Black communities, he says.
“The issue comes down to disparities that exist in access to healthcare or underlying conditions,” Checkley says.
The four variants, including the Delta variant, have been shown to respond well to the vaccines, Checkley says. However, Checkley notes that scientists and health officials are still trying to understand the duration of immunity that vaccines will grant against the virus and its variants.
“Our experience with COVID-19 vaccines is still relatively new. We only have populations that have been vaccinated from anywhere from six months to nine months, depending on the trials, Checkley says. “As we continue to follow individuals who have received vaccines … we will learn more about the process of immunogenicity.”
Checkley says that there is a possibility that vaccinated populations will need to begin receiving booster shots, which will “boost” the immune system to continue virus immunity.
“All the vaccine makers are thinking of whether there will need to be adjustments to take into account the variants. While SARS-CoV-2 is mutating and changing, its rate of change is much slower than other viruses like the influenza virus that requires tweaking of its vaccine for yearly shots,” Checkley says.
The requirement of booster shots could provide another logistical challenge for countries that have been struggling to administer initial vaccinations of their populations, Checkley says.
“It means that our governments and also the groups that are in charge of public health across the world need to have a coordinated approach to provide vaccines in a way that protects our population,” Checkley says.
Checkley says that the tweak that the flu shot receives each year can’t really compare to the booster shots vaccinated people might need since the COVID-19 vaccines are 50-55% more effective than flu shots.
Overall, Checkley says, the COVID vaccines’ efficacy is quite high for preventing serious cases and hospitalizations.
According to the CDC, 70.4% of adults have received at least one vaccine shot, while 49.6% of the population is fully vaccinated. New vaccinations have risen by 16% recently as the population has become more aware of the highly spreadable variant.
Checkley attributes this plateau and vaccine hesitancy partly to concern about using newer technology, as COVID-19 vaccines are the first to use mRNA.
“There’s always that concern about the new technology and its effect on genetic code. It’s important to continue with educating and say, ‘There is no genetic material that is being introduced into your genetic code. This is just the genetic code for the virus that helps produce antibodies against the virus,’” Checkley says.
He adds that the fear of side effects has deterred some from receiving the vaccine, noting specifically the Johnson & Johnson vaccine that resulted in seven to eight cases of severe blood clots out of millions vaccinated.
More education is the key to working through vaccine hesitancy and reminding people that the vaccine is safe, he says, and that increasing vaccination rates helps protect the larger population.
“The more people that are vaccinated, the harder it is for the virus to be transmitted,” Checkley says. “If there are enough people vaccinated, there won’t be an opportunity for the virus to continue to spread and mutate.”
—Written by: Melissa Perez-Carrillo
—Interviewed by: Noemi Vega, Mariángel Villalobos,
Melissa Perez-Carrillo, and Vanessa Romero Gutierrez
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