A panel of public health experts on July 30 debated the efficacy of COVID vaccines against the dominant Delta variant, concluding that — though the vaccines are 80 to 90% effective against hospitalizations and deaths — they are less effective in containing the spread of the potent mutant strain.
Speakers at the news briefing, organized by Ethnic Media Services, included Drs. Monica Gandhi, Professor of Medicine at UC San Francisco’s School of Medicine; Tiffani Jenae Johnson, of the UC Davis Health Children’s Hospital; Ben Neuman, chief virologist at the Global Health Research Complex at Texas A&M University; and Dali Fan of UC Davis Health.
The experts spoke amid a rise of new infections from the Delta variant, and a new report from the Centers for Disease Control which showed a rise in breakthrough infections – people who were fully vaccinated, but still had a symptomatic infection.
Breakthrough infections in fully-vaccinated people are on the rise. A CDC internal memo that was first obtained by The Washington Post last week, reported that an estimated 32,000 fully vaccinated people are getting symptomatic breakthrough infections each week among the 162 million vaccinated Americans. The report did not include the numbers of asymptomatic people who were also infected.
The report indicated that the delta variant spreads as fast as chicken pox and faster than smallpox, Ebola, the 1918 flu, MERS and SARS and the common cold.
Mask mandates have once again been re-implemented in several communities across the country as several studies concluded that fully vaccinated people are still capable of transmitting the Delta variant.
“This is an amazingly effective vaccine at preventing severe disease hospitalizations and deaths. That was actually the promise of the vaccines. I think it’s important to still say that the vaccines work,” said Gandhi.
The Delta variant is very transmissible in that it has high viral loads, which even in fully vaccinated people can stop the body from using its B cells to produce the antibodies that get into their nose and cause transmissions to others, explained Gandhi.
She agreed with the CDC’s recommendation of wearing masks indoors in areas with high viral load circulations, and noted that this could prevent the vaccinated from getting breakthrough infections.
Neuman, the Texas A&M virologist, summated six studies that determined various levels of efficacy of vaccines against the Delta variant. The single-dose Johnson and Johnson vaccine, and other adenovirus vaccines, had a slightly lower rate of efficacy — 7 % — than the two-dose Moderna or Pfizer, which employs mRNA. He said the difference was negligible, however, and would not be concerned about giving either of the vaccines to his family.
Studies conducted in Israel and the United Kingdom showed that 80 to 90 % of people who were fully vaccinated would not get infected with COVID, and moreover, would not transmit the virus.
“At a population level, an 80 to 90% effective vaccine is an absolute godsend, which would be extremely effective attending a disease like COVID-19,” said Neuman.
The researcher also noted a study conducted in Hyderabad, India studied hospitalized people and noted that those who were fully vaccinated were 50 % less likely to have severe outcomes from COVID, such as ventilator use and death.
Neuman remarked that the number of breakthrough infections was not a reason to stop vaccinating. “We’re trying to switch off a fire hose here, which is the number of new cases that are coming out, and vaccinating the unvaccinated is the way to do that.”
“When we talking about breakthroughs, we’re cleaning up drips off the floor. Those are very important on an individual level but they’re not a reason not to vaccinate. Vaccination still looks like our only real way out of this,” he said.
The vaccines decrease in efficacy by 6 % every month, and may be effective in the long-term for a maximum of 18 months, said Neuman.
Dr. Fan of UC Davis Health, said boosters were likely unnecessary at this point, except for residents of long-term care facilities, adults over 65 years of age, health care professionals, and immunocompromised people. “The biggest problem for the immunocompromised population is that they do not produce enough antibodies, no matter how many doses of vaccines you give them,” he said.
Studies out of Europe show remarkable efficacy in “mix and match” boosters — people who got the AstraZeneca vaccine to start and then followed up with a Pfizer booster, noted Fan. Pfizer is preparing to submit its data to the FDA, recommending that boosters be given 6 to 12 months after the initial series.
Dr. Johnson of UC Davis Children’s Health Center, spoke about the barriers that prevent low-income minorities from getting vaccinated, such as health care deserts, lack of transportation, the inability to take time off to get vaccinated and also to deal with known side effects.
“We’ve had some politicians explicitly say it’s time to start blaming the unvaccinated folks as this pandemic worsens. But It’s really a lot more nuanced than just pointing the fingers at the unvaccinated as we continue to see spikes in COVID,” she said. (By Sunita Sohrabji/Ethnic Media Services Contributing Editor)