COVID-19 vaccine maker Moderna will make a third booster shot for its two-dose vaccine available to Americans by the fall, CEO Stéphane Bancel said this week.
Moderna's vaccine is more than 90% effective against the studies show. What remains unclear is how long immunity from the virus lasts.six months after the second shot,
The same is true of Pfizer's two-dose COVID-19 vaccine.
"There will be likely a need for a third dose, somewhere between six and 12 months. And then from there, there will be an annual revaccination. But all of that needs to be confirmed," Pfizer CEO Albert Bourla said Thursday at a virtual event hosted by CVS Health.
A thirdagainst the virus is not yet required, but health experts say it could provide additional immunity against COVID-19 variants that are beginning to spread to the U.S. from Brazil, South Africa and the United Kingdom.
"All of those have some suspicion of being able to evade protection that's provided by the vaccines," said Justin Gill, an urgent care nurse practitioner, told CBSN.
There is also a chance that fully vaccinated individuals could still become infected with the virus, as none of the available vaccines provide 100% immunity against COVID-19.
"We do know that some [who are fully vaccinated] still get infected and test positive for COVID-19, but there's still a lot of unknowns about those individuals that do end up testing positive," Gill said.
Such "breakthrough" infections are thought to very rare, but can occur when vaccinated individuals are exposed to variants or a significant viral load.
While drugmakers develop a booster shot, individuals who've already received two doses of the Moderna or Pfizer vaccine can rest assured they are well protected against COVID-19.
"In the end, it still provides great protection," Gill said. "But we know that some will still get the COVID-19 virus, and it's essential that they still continue to follow those public health guidelines, wear a mask and remain vigilant when they are around other individuals."
Vaccine confidence has risen among individuals across the U.S. as more Americans have seen their friends and family members get vaccinated, according to the Kaiser Family Foundation.
To date, roughly 38% of the U.S. population have received at least one dose of the vaccine and 24% are fully vaccinated, according to the Centers for Disease Control and Prevention.