San Antonio Express-News (Sunday)
Virus variants boost calls to stay on guard, get shots
More mutations are assumed to be in S.A. or arriving soon
A more transmissible form of the coronavirus is now circulating in San Antonio, but other variants have the potential to pose a greater threat to the community.
Available vaccines appear to provide strong protection against B.1.1.7, the more contagious variant that was first detected in Britain and has been identified in two Bexar County residents. That version of the virus may also struggle to find new hosts because of rising immunity and existing health safeguards.
But experts fear that other mutations first found in South Africa and Brazil could lessen the benefits of such immunity, complicating efforts to bring the pandemic to heel. While those variants have not yet been confirmed in San Antonio, health officials say it is safe to assume they are here or will be soon. Just last week, a case of B.1.351, the South Africa variant, was identified in the Houston area.
“Absence of evidence doesn’t mean the evidence is absent,” said Anita Kurian, head of the Metropolitan Health District’s communicable disease division. “Assume that the strains are already here.”
The emergence of coronavirus variants, while not unexpected, comes as the United States works to reduce its high infection rates and rectify a haphazard and uneven vaccine distribution and as the manufacturers of several other vaccine candidates advance toward regulatory approval. Efforts are still underway to assess how the existing group of vaccines perform against different variants.
Experts say the evolution of the virus raises the urgency for vaccinating the public and practicing behaviors such as masking and physical distancing
“If we decrease the number of infections, then we decrease the potential for more virus mutations to occur.”
Dr. Thomas Patterson, leader of the division of infectious diseases at UT Health San Antonio
that reduce further transmission. As the virus continues to spread, it has more opportunities to mutate in ways that could evade existing treatments and immune responses.
“This is a reminder that we’re not out of this yet,” said Dr. Jason Bowling, an infectious disease specialist with UT Health San Antonio and University Health.
Across the country, health officials are tracking the spread of several coronavirus variants by use of genetic sequencing, which allows scientists to chart changes in the virus over time. As of Thursday, 37 states had reported nearly 1,000 cases of B.1.1.7, which is expected to become predominant in the U.S. by next month, according to the Centers for Disease Control and Prevention. The agency reports 13 cases of B.1.351 and three instances of P.1, a variant suspected of causing reinfections in Brazil.
The Texas Department of State Health Services laboratory has sequenced 169 samples from Bexar County residents, spokeswoman Lara Anton said. Several other public and private labs are also processing specimens. Metro Health has sent its own samples to the state lab for sequencing, and it has urged area health care providers to send samples in cases where the person has traveled, especially to areas where variants are present, or became infected after vaccination.
The two cases of B.1.1.7 variant in San Antonio were detected in samples collected during the last week of January. While Kurian said case investigators from Metro Health have been unable to reach one of the individuals after repeated attempts, the other person had no history of travel. Both are past their periods of isolation.
She said there is not yet enough evidence to indicate when the variant arrived or what role it may have played in San Antonio’s winter coronavirus surge, if any.
Like any RNA virus, the coronavirus that causes COVID-19 accumulates genetic mutations as it reproduces and spreads from person to person. Most of these changes, which occur more slowly than with influenza, have no significant effect on transmission or disease severity, Bowling said, so they are paid little attention.
He noted that these are not the first variants to sweep through the country over the past year. Until recently, there had not been concerted genetic sequencing,
a process that is time-consuming, laborious and more limited in the U.S. than in other countries.
Mutations only become a problem when they allow the virus to more effectively spread or evade the immune systems of their hosts. In the case of B.1.1.7, a mutation in the spike protein appears to allow the virus to more easily invade cells, increasing its contagiousness by an estimated 30 to 40 percent. When the virus surged in the United Kingdom in December and January, the variant rapidly became prevalent there.
Higher rates of transmission means more people could become infected more quickly, Bowling said, further taxing a health care system that is already stretched thin and overworked.
However, spread of this version of the virus is also coinciding with the gradual administration of the Pfizer and Moderna vaccines to the most vulnerable segments of the population in San Antonio.
Those vaccines still appear to protect people against B.1.1.7, Bowling said, which should temper the effects of the variant, especially when it comes to incidence of severe disease. Other vaccine candidates, including those produced by Johnson & Johnson and Novavax, also appear to remain protective.
“That’s the good news, that the vaccine is still very effective,” Bowling said.
Concern but not panic
While B.1.1.7 could potentially lead to an increase in cases in San Antonio because of its heightened contagiousness, it’s not the variant that most worries Juan Gutiérrez.
For the past year, the professor and chair of mathematics at the University of Texas at San Antonio has analyzed data on the coronavirus to model the trajectory of the pandemic. Before the holidays, his model accurately predicted that San Antonio’s coronavirus cases could roughly double by January.
While data was scant at the beginning of the pandemic, he said, there is now a wealth of information about how the virus spreads among populations and its evolution over time. That greatly increases the confidence with which Gutiérrez and his collaborators can make educated projections.
From the start, Gutiérrez said modeling has consistently estimated that 900,000 Bexar County residents could become infected and 16,000 could die if no public health interventions were implemented.
While the official tally for Bexar County currently stands at around 186,000 infections, Gutiérrez
said the true number of cases is probably closer to 400,000 or 500,000 because of asymptomatic carriers and other cases that may have gone unreported. That would mean that about 1 in 4 people in the county have already been infected.
That assumption, coupled with the current conditions — where many people are working from home, wearing masks and avoiding gatherings — would likely cause cases in San Antonio to level off at about 250,000 confirmed infections, Gutiérrez said.
Additionally, many of the most at-risk people have already gained some immunity, either through infection or inoculation.
“All those things come down, converge, and the final effect is the disease is slowed down,” he said.
As a result, he said, B.1.1.7 may not spell disaster — so long as public health restrictions are not lifted too soon.
“Keep containment measures in place,” Gutiérrez said. “We need to keep wearing those face masks until vaccination is widely available. If we lower the guard, these numbers can still go up, substantially up.”
The more concerning scenario, Gutiérrez said, is if other variants prove to be particularly adept at reinfecting people, causing cases to steeply climb again and potentially prolong the pandemic. He is worried about reports of rising COVID death rates in Africa, where several variants are spreading.
Gutiérrez and other experts say another surge driven by variants is not out of the question, particularly if health measures were relaxed.
“We could have another surge,” Bowling said. “It’s important to recognize. We don’t want to be Pollyanna or overly optimistic, that this is the last time we’ll have a surge like this.”
Should that happen, infectious disease experts say, the population likely would not be as vulnerable as it was at the beginning of the pandemic.
“We need to be concerned, but I don’t think we need to be panicked,” said Dr. Thomas Patterson, who leads the division of infectious diseases at UT Health San Antonio.
Even if existing vaccines are not as effective as they were against previous versions of the virus, Bowling said, that does not equate to no protection at all.
For example, the Johnson & Johnson vaccine was found to be about 66 percent effective overall — 72 percent in the U.S. and 57 percent in South Africa, where a variant was circulating. That level of protection is on par with the annual flu vaccine. And, like with the flu shot, a coronavirus vaccination should still provide strong protection against severe illness, hospitalization and death, blunting the worst effects of the pandemic.
People should not allow themselves to become too discouraged by lowered efficacy rates, Bowling said.
“That’s still a vaccine worth getting,” he said.
The vaccines made by Pfizer and Moderna can be easily updated, and manufacturers are already working on boosters for emerging variants.
Patterson said it still remains unclear how long protection from vaccination will last or the extent to which inoculation reduces transmission.
But he said one thing was certain: Continuing to reduce infection rates will help guard against future variants that could reduce vaccine efficacy further. Even with vaccine availability expected to increase over the next few months, the public’s continued cooperation with health guidance is still important, he said.
“If we decrease the number of infections, then we decrease the potential for more virus mutations to occur,” Patterson said.