• Moderna expects people will need to get a third dose of its COVID-19 vaccine before this winter.
  • Going out eight months, the vaccine’s protection could wane, Moderna executives said.
  • “We believe a booster dose is likely to be necessary this fall,” President Stephen Hoge said.

The biotech firm Moderna on Thursday said it expected that a third dose of its COVID-19 vaccine would be necessary before the winter, saying protection from the shot could fade over time.

On an earnings call with Wall Street analysts and investors, Moderna executives provided the clearest view yet of why and when people may need to get booster shots. Overall, the biotech’s perspective suggests a long war ahead with the coronavirus, even after a booster dose.

“This is not the last round of the fight with SARS-CoV-2,” said Stephen Hoge, Moderna’s president, using the virus’ formal name. “We expect it to have at least a couple more rounds, and maybe annually, we’re just going to continue to fight this virus back.”

In making the case to start rolling out a third dose, Hoge cited research suggesting waning immunity against the virus. The Delta variant in particular can partially evade the vaccine’s protection, resulting in more infections among the fully vaccinated.

Moderna presented data on Thursday showing a noticeable drop in antibody levels — a key element of the immune response — six to eight months after the second dose. The information hasn’t been reviewed by outside scientists or published in a scientific journal.

Moderna President Stephen Hoge. 

“We believe a booster dose is likely to be necessary this fall, particularly in the face of the Delta variant,” Hoge said.

Read more: We got an exclusive look inside Moderna’s labs, where the biotech upstart is planning what comes after its blockbuster coronavirus vaccine

Selling millions of booster shots could provide a big financial boost to Moderna, whose first and only commercial product is the vaccine. The company has charged richer nations other than the US about $32 to $37 a dose and offers shots to poorer countries at a lower price.

The company has sold $5.9 billion worth of coronavirus shots so far this year. Its success in quickly creating the shot and pumping out doses has propelled the biotech to a $168 billion valuation.

While Moderna is developing vaccine candidates tailored to fight variants including Delta, Hoge said the initial booster would likely be the original formulation of Moderna’s vaccine given at half the strength of the first two shots.

Hoge said that in reviewing laboratory testing of a third dose, Moderna found that its initial vaccine given as a third shot would be “more than sufficient as a booster” even against the Delta variant.

Moderna’s immunization is given as two shots about four weeks apart. Moderna said on Thursday that the two-dose vaccine had an efficacy of about 93% up to six months after the doses.

Pfizer, which makes another COVID-19 vaccine, has forcefully made the case to roll out boosters as soon as six months after the second dose. Some countries seem convinced. Israel started rolling out shots to some older citizens. Germany and France have announced plans to start boosting older and vulnerable people in September.

These countries have so far ignored the World Health Organization’s plea to rich nations to hold off on boosting their populations given low initial vaccination rates in many low- and middle-income countries.

Dr. Paul Offit, a vaccine developer on the Food and Drug Administration’s advisory committee on vaccines, told The New York Times that Moderna’s data didn’t justify rolling out boosters yet. Offit said he wanted to see data showing that the shots weren’t preventing severe disease anymore.

“You want this vaccine to protect against the kind of illness to cause you to seek medical attention, or be hospitalized,” he said. “And until you see any evidence that that isn’t true, then you don’t need a booster dose.”

Moderna anticipates more variants and is developing a multivalent shot

Looking to 2022 and beyond, Hoge said he expected new variants of concern to pop up. Moderna has already agreed to sell as much as $20 billion worth of its vaccine in 2022.

Hoge highlighted five concerning mutations across the Beta and Delta variants — three in the Beta variant and two in the Delta variant — that appeared to help the virus partially evade vaccine protection.

The executive said it was “logical” that these five mutations “might find some way to combine in new and potentially scary ways.”

To prepare for the possibility, Moderna is developing so-called multivalent vaccines, or shots to protect against multiple strains of the virus.

“The goal of the multivalent platform is to continue to try and stay ahead of where the virus is going by combining different antigens against emerging variants of concern,” Hoge said.

Moderna’s view is that the virus will eventually become endemic.

“We really do believe the virus is here to stay for the long term,” Hoge said. “And therefore there’s going to be a need to regularly boost, particularly high-risk older populations, against SARS-CoV-2 into the future.”