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A coronavirus vaccine may arrive next year. ‘Herd immunity’ will take longer

Anthony Fauci, the foremost infectious diseases expert in the U.S., has said a coronavirus vaccine could be available within 12 to 18 months. His timeline isn’t just ambitious; it’s unprecedented speed for a vaccine, which typically take many years of testing to make it to market.

The challenges are many. Any vaccine available at such speed likely won’t have data definitively proving it is safe and effective at preventing infection, forcing regulators to make a difficult choice. A vaccine for the new coronavirus, currently confirmed to have infected more than 3.4 million people worldwide through May 4, would have to be manufactured for the masses far faster, and at wider scale, than ever before. And there’s no guarantee that a vaccine could provide the broad protection necessary to curb the coronavirus pandemic.

“I think the 12 to 18 months that has been mentioned is optimistic,” Walter Orenstein, an Emory University medical school professor and associate director of the Emory Vaccines Center, said. “It’s possible if everything goes right, but with most vaccines it takes longer than that.”

Raising the stakes on clinical development is the Trump administration’s “Operation Warp Speed,” which aims not only to have an approved vaccine, but also enough doses for every American by January. The president is asking the sector to compress a development cycle that can sometimes take decades into just 12 months — a feat that will require Americans to accept higher-than-usual safety risks along with the possibility the first vaccine they receive won’t work that well.

Population protection

Herd immunity, as it is known, occurs when enough people are immune to an infectious disease to prevent its spread.

Achieving herd immunity to SARS-CoV2 infection may be the biggest step toward returning social and economic activities to normal, as social distancing rules may persist while the virus circulates and people continue to get sick and die. Economic forecasters’ assumptions about a future rebound rely on such an outcome.

Typically, herd immunity isn’t achieved in a year or two. Vaccines can take up to a decade or more to win approval based on their ability to prevent disease in tens of thousands of people. For example, GlaxoSmithKline’s vaccine Shingrix won approval on the basis of results in nearly 33,000 patients followed for four years, in which the vaccine reduced shingles cases by around 97% when compared with placebo.

Given the urgency of the coronavirus pandemic, however, the Food and Drug Administration is likely to accelerate the standard process and grant a vaccine an emergency use authorization — a limited declaration that, while not equivalent to a standard drug approval, makes a medicine available during public health emergencies. That decision may come after a vaccine has shown only whether it can induce an immune response in a comparatively small group of people, not that it can safely prevent infections.

In such a scenario, public health officials would prioritize high-risk groups, such as healthcare workers, for the first vaccines, who in turn would serve as a test case to determine how well the vaccines actually protect people from coronavirus disease.

“We’ll learn as we go,” said Paul Offit, director of the vaccine education center at Children’s Hospital of Philadelphia, in an interview. “You’re going to really see just how effective it is, just how safe it is, when it’s already in tens of thousands of people or hundreds of thousands of people.”

But at the outset, only the priority groups that qualify would be protected. Rolling out a mass immunization campaign that reaches 70% to 85% of the population, a threshold necessary to keep SARS-CoV-2 at bay, could take years.

Scaling up

Getting to a point where mass immunization is possible will require the biopharmaceutical industry to clear several difficult hurdles.

Among them: proving that the coronavirus’ signature “spike” protein is the correct target; that vaccines training the body to recognize that protein trigger a deep and durable immune response without causing other health problems; that companies can meet the massive demand for an effective vaccine; and that the healthcare system can subsequently mount a mass campaign.

A two- to three-year timeline, then, is a more realistic estimate for when a vaccine will be widely available to the public, Geoffrey Porges, an analyst at SVB Leerink, recently wrote. Availability, he noted, is just the first step.

“In the remote possibility that an approved, effective, safe general use vaccine was available a year from now, it would still take several years to confer sufficient ‘herd immunity’ to prevent endemic spread of COVID-19,” Porges wrote in an April 21 note to clients. “We believe that achieving herd immunity sufficient to prevent epidemic spread is likely to occur in 2023 or 2024.”

Types of vaccines being developed against coronavirus
Type of vaccine How it works Number in development
Inactivated virus Coronavirus exposed to an agent that keeps it from being infective while still stimulating immune response 5
Weakened virus Coronavirus able to infect cells to induce immunity, but weakened enough that it doesn’t cause disease 3
DNA-based Gene to produce coronavirus spike protein is delivered to cell nucleus 9
RNA-based Genetic instructions to produce coronavirus spike protein are delivered to cells 16
Non-replicating viral vector Harmless virus engineered to carry DNA code for spike protein 14
Replicating viral vector Weakened virus engineered to carry DNA code for spike protein 11
Virus-like particle Molecules that look like coronavirus but can’t infect cells 6
Protein subunit Small part of a virus and an accompanying ingredient that stimulates immune response 32

Source: Milken Institute

Biotech and pharma companies say they are readying themselves for a Herculean manufacturing effort, preparing early in case a viable prospect emerges from about 100 projects that have already begun. Companies large and small are risking cash by making huge amounts of vaccine doses before completing clinical trials.