When Pfizer Inc. and BioNTech SE reported their successful coronavirus vaccine trial results on Nov. 9, the news sparked optimism around the globe that there was finally light at the end of the long, dark tunnel. Investors rushed to bid up stocks—not just those of vaccine makers, but of a wide swath of ordinary companies expected to benefit once the pandemic moves into the rearview mirror. Yet there are still many hurdles before vaccines get into widespread use and Covid-19 is history.
Questions about production, distribution, and, most important, the capability of the shot itself still need to be answered. Pfizer’s late-stage trial started less than four months ago, and how long the vaccine will confer protection is unknown. “The key question still centers upon time,” says Michael Kinch, a drug development expert and associate vice chancellor at Washington University in St. Louis. “Will time tell us that the protection remains useful for the larger population?”
In a remarkable scientific feat—achieved without research, development, or manufacturing funding from the U.S. vaccine accelerator known as HDWX2QC” itemprop=”suid”/> Operation Warp Speed—Pfizer and BioNTech produced positive results almost 11 months after Covid’s emergence in China. An early analysis of data from the trial of more than 40,000 volunteers suggested the vaccine was more than 90% effective in preventing the illness, the partners said. The likely success of the first vaccine in a large, late-stage trial raised hopes that others, like those being developed by Moderna Inc. and the partnership of AstraZeneca Plc and the University of Oxford, will also work.
While Pfizer’s announcement signals its vaccine could be the first to gain an emergency go-ahead from the U.S., others are only slightly behind in testing. And since global demand for the vaccines will be so high, shots from multiple companies will likely be needed to immunize a large portion of the world’s population quickly.
Moreover, the Pfizer vaccine has a notable practical limitation: It must be kept frozen at an ultralow –94F until a few days before it is used. That requires special freezers or dry ice packs, complicating distribution. Moderna is thought to be just a few weeks behind Pfizer in the testing process. It’s working with the same messenger RNA technology, which uses the body to produce a key coronavirus protein, stimulating the immune system to make antibodies to fight the virus. Moderna says its vaccine can be kept in regular freezers; some other vaccines don’t need to be frozen at all.
Pfizer’s vaccine also requires two shots to be given three weeks apart before significant protection kicks in. While most other vaccines in late-stage testing also require multiple shots, Johnson & Johnson’s may work after just one, which would enable more people to get protection faster. Results of a 60,000-participant J&J trial may come by yearend.
Whichever vaccines get emergency authorizations, supplies will be very limited at first. Pfizer has said it expects to have as many as 50 million doses available by the end of the year, or enough for 25 million people, though it hopes to produce up to 1.3 billion doses next year. If Pfizer gets crucial data needed for the vaccine to gain emergency regulatory clearance, a panel of doctors and public-health experts convened by the U.S. Centers for Disease Control and Prevention will make vital recommendations about who should be inoculated first. The group, called the Advisory Committee on Immunization Practices, is expected to make recommendations shortly after a vaccine garners regulatory clearance. People at high risk of infection, such as health-care workers, or of experiencing a severe case—the elderly and those with chronic conditions—will likely be first in line. Once these recommendations are in place, vaccinations can begin.
Who gets which vaccine will also depend in part on deals that governments have made with drug companies. The U.S. agreed in July to pay Pfizer $1.95 billion for 100 million doses of its vaccine—the equivalent of $39 for a two-shot immunization, a price BioNTech has said could become a benchmark for developed nations—once the shot is cleared, with an option to buy 500 million more. The European Union signed a deal to buy 200 million doses, with an option to buy an additional 100 million. The UK. struck its own supply agreement, while Japan and Canada also have pacts with the two partners.
AstraZeneca and its partner, Oxford, agreed to deliver 100 million doses of their vaccine to the UK., which will be the first country to get access should the shot succeed, the British government said in May.
The expense of deploying the Pfizer shot will likely heighten existing fears that wealthier nations will get the best vaccines first, despite a World Health Organization-backed effort called Covax that aims to equitably deliver vaccines all over the world.
It also presents a choice now faced across the developing world: to pay for the expensive construction of subzero storage infrastructure for what seems like a sure bet, or wait for a slower, more conventional vaccine that brews batches of protein or inactivated viral particles in living cells and can be delivered through existing health-care networks.
“If there is a protein-based vaccine that could achieve the same effect as an mRNA vaccine does and there’s the need to vaccinate billions of people every year, I’d go for the protein-based shots in the long run,” says Ding Sheng, director of the Beijing-based Global Health Drug Discovery Institute, which has received funding from the Bill & Melinda Gates Foundation.
Even the U.S., which has lined up hundreds of millions of doses through the Warp Speed program, would need all six of its suppliers to be successful for the country to reach herd immunity by June, according to researcher Airfinity Ltd. Because the rollout of any shots will not happen overnight, masks, distancing, testing, and contact tracing will still be vital, says Ohid Yaqub, a senior lecturer at the University of Sussex’s Science Policy Research Unit. And since the mRNA technology used in the Pfizer/BioNTech vaccine has never been deployed in humans before, people who get the vaccine will need to be monitored. “It will be crucial to track the safety and efficacy over the coming weeks and months,” says Kinch, the Washington University expert. “If nothing else, we have learned that we need to look to the long term.” —With Riley Griffin and Naomi Kresge
Read more: How Close Are We to a Coronavirus Vaccine? Tracking Covid-19 Drugs, Treatments