If You Got This One Vaccine, Get a Booster Now, Virus Expert Warns
The spread of the Delta variant means you might need an additional dose.
The rollout of vaccines has helped drop the national daily average of new COVID cases in the U.S. over the past six months. But as time passes, experts and officials have begun to question when booster shots will be needed to make sure they can still protect against the virus. The recent arrival and spread of the Delta variant—which is believed to be 60 percent more transmissible than the contagious Alpha variant—has increased pressure on the situation, with some officials concerned that new outbreaks could soon hit areas with low vaccination rates. But according to Angela Rasmussen, PhD, a virus expert and research scientist with the Vaccine and Infectious Disease Organization (VIDO), anyone who got the Johnson & Johnson vaccine will likely need a booster shot as soon as possible.
In a tweet posted on June 22, the Saskatoon, Canada-based Rasmussen addressed the idea of administering a second shot to top up the single-dose vaccine as questions about its ability to protect against the latest variant have caused concern among some officials. "If you are in the U.S. and got J&J [Johnson & Johnson], I encourage you to talk to your provider about whether this is something you should think about. If you live in a community with overall low vaccination, I'd suggest you strongly consider doing so," she urged.
Rasmussen argued that adding a second shot of an mRNA vaccine such as Moderna or Pfizer would be more likely to provide the protection needed as the Delta variant spreads. In a thread of tweets, she explained: "We know heterologous (mix and match) vaccination with an adenovirus-vectored vaccine (J&J, AstraZeneca) is safe and produces robust immune responses. We know that 2-dose regimens of mRNA or AstraZeneca are highly protective against the Delta variant, but a single dose is not. [And] we know that the single-dose J&J regimen is highly protective against severe disease but not as protective against symptomatic disease as mRNA, meaning it's less protective against infection."
She added that while there isn't enough data to see exactly how effective the J&J vaccine is against the Delta variant or if an mRNA booster will offer added protection, she was confident that the extra dose would behave similarly to other vaccines and increase overall efficacy. And since symptomatic carriers are more likely to spread the virus, the extra doses could help slow or prevent serious outbreaks.
While the Centers for Disease Control and Prevention (CDC) says more data is needed before a second shot can be recommended, Rasmussen's advice has been echoed by a growing number of experts who believe those who got the Johnson & Johnson vaccine need to get a booster. "There's no doubt that the people who receive the J&J vaccine are less protected against disease" than those who get two doses of the other shots, Michael Lin, PhD, professor of neurobiology and bioengineering at Stanford University, told Reuters. "From the principle of taking easy steps to prevent really bad outcomes, this is really a no-brainer."
Similar to some other experts, Rasmussen said that she herself had just taken an mRNA booster after having received a dose of the J&J vaccine in April. She urged officials to address the growing issue as soon as possible.
"We shouldn't wait to make recommendations about this," she wrote. "In the U.S. and increasingly in Canada, there are ample supplies of mRNA vaccines that will expire before they can be shipped to other countries. We only need to look to the rise of delta in the U.K. to see the crucial importance of getting as many people fully vaccinated as possible."