US vaccine test
In this file photo taken on August 13, 2020, Sandra Rodriguez, 63, receives a COVID-19 vaccination test from Yaquelin De La Cruz at the Research Centers of America (RCA) in Hollywood, Florida. The Trump administration has urged US states to get ready to distribute a potential Covid-19 vaccine by November 1. Image Credit: AFP

Washington: The Centres for Disease Control and Prevention has notified public health officials in all 50 US states and five large cities to prepare to distribute a coronavirus vaccine to health care workers and other high-risk groups as soon as late October or early November.

The new CDC guidance is the latest sign of an accelerating race for a vaccine to ease a pandemic that has killed more than 184,000 Americans. The documents were sent out on the same day that President Donald Trump told the nation in his speech to the Republican National Convention that a vaccine might arrive before the end of the year.

See more

Over the past week, both Dr Anthony Fauci, the country’s top infectious disease expert, and Dr Stephen Hahn, who heads the Food and Drug Administration, have said in interviews with news organisations that a vaccine may be available for certain groups before clinical trials have been completed, if the data is overwhelmingly positive.

Public health experts agree that agencies at all levels of government should urgently prepare for what will eventually be a vast, complex effort to vaccinate hundreds of millions of Americans. But the possibility of a rollout in late October or early November has heightened concerns that the Trump administration is seeking to rush the distribution of a vaccine - or simply to hype that one is possible - before Election Day on Nov. 3.

Daunting challenge

For an administration that has struggled with the logistical challenges of containing the coronavirus, the distribution of millions of vaccines that must be stored in subzero temperatures and provided first to high-risk groups through America’s flawed, fragmented health care system would be a daunting challenge. Even the CDC’s guidance acknowledged that its plan was hypothetical and based on the need to immediately begin organising the gigantic effort that would be required if the FDA were to allow the use of a vaccine or two this year.

The CDC plans lay out technical specifications for two candidates described as Vaccine A and Vaccine B, including requirements for shipping, mixing, storage and administration. The details seem to match the products developed by Pfizer and Moderna, which are the furthest along in late-stage clinical trials. On Aug. 20, Pfizer said it was “on track” for seeking government review “as early as October 2020.”

“This timeline of the initial deployment at the end of October is deeply worrisome for the politicisation of public health and the potential safety ramifications,” said Saskia Popescu, an infection prevention epidemiologist based in Arizona. “It’s hard not to see this as a push for a preelection vaccine.”

Detailed scenarios

Three documents were sent to public health officials in all states and territories as well as officials in New York, Chicago, Philadelphia, Houston and San Antonio on Aug. 27. They outlined detailed scenarios for distributing two unidentified vaccine candidates, each requiring two doses a few weeks apart, at hospitals, mobile clinics and other facilities offering easy access to the first targeted recipients.

Read more

The guidance noted that health care professionals, including long-term care employees, would be among the first to receive the product, along with other essential workers and national security employees. People 65 or older, as well as Native Americans and those who are from “racial and ethnic minority populations,” or incarcerated - all communities known to be at greater risk of contracting the virus and experiencing severe disease - were also prioritised in the documents.

That’s a positive development, “so it doesn’t just all wind up in high-income, affluent suburbs,” said Dr. Cedric Dark, an emergency medicine physician at Baylor College of Medicine in Texas.

Pfizer and Moderna

Many of the details listed for the two vaccines - including required storage temperature, the number of days needed between doses, and the type of medical centre that can accommodate the product’s storage - match what Pfizer and Moderna have said about their products, which are based on so-called mRNA technology. Neither company responded to requests for comment.

The scenarios, which assume that the two vaccines will demonstrate sufficient safety and effectiveness for an emergency authorization from the FDA by the end of October, noted that Vaccine A, which seems to match Pfizer’s, would have about 2 million doses ready within this time frame, and that Vaccine B, whose description matches Moderna’s, would have about 1 million doses ready, with tens of millions of doses of each vaccine ready by the end of the year. Although it’s possible that some promising preliminary data may emerge by the end of October, experts are skeptical.

“The timeline that’s reported seems a bit ambitious to me,” Dark said. “October’s like 30 days away.”

Long-term trials needed

Trials that test a vaccine’s effectiveness can take years to yield reliable results. It’s possible to draw conclusions sooner “if there is an overwhelming effect” in which vaccinated people appear to be far better protected from disease, said Padmini Pillai, a vaccine researcher and immunologist at MIT.

But there can be significant risks in approving a vaccine for broad use in the public before Phase 3 clinical trials involving tens of thousand of participants are completed. Rare but dangerous side effects may only surface over time, after such large numbers of people have received the vaccine.

And data gathered early in a trial might not hold true months down the line. Researchers also need time to test large numbers of people from a variety of backgrounds to determine how well the vaccine works in different populations - including the vulnerable communities identified in the guidelines.

Should any of these snags occur, Pillai said, “all of this together could diminish public trust in the vaccine.”