Coronavirus vaccines coming, but Johns Hopkins experts say some vital questions remain unanswered

Vaccines designed to mitigate the scope and severity of the coronavirus pandemic could be distributed to millions of Americans before the end of December, health officials said this week. But much about the vaccines — such as the duration of immunity they offer, possible long-term side effects and variance across different ages, races and ethnicities — will likely take another year or so to understand.

Three vaccine candidates — Pfizer’s, Moderna’s and AstraZeneca’s — have reported promising results from their late-stage Phase 3 clinical trials and will seek emergency use authorization from the U.S. Food and Drug Administration. The FDA says it will consider the first request from Pfizer next week.


The promise of a vaccine comes as COVID-19 wreaks new havoc across the country. More people are being hospitalized and dying of the disease caused by the virus than at any other point during the pandemic, and hospitals are reporting troubling signs of strain.

But even if vaccines become widely available before the end of the year, many more months of study, clinical trial testing and research will be required before vaccines can be deemed effective, said Dr. William Moss, executive director of the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health, during a virtual media briefing Thursday.


“It will be important to continue to follow up with individuals who get the vaccine,” said Moss, also an epidemiology professor at Hopkins’ school of public health. “Other [vaccines] ... may turn out to be even better.”

The initial vaccines are expected to require recipients to get two separate doses, and Pfizer’s and Moderna’s also require storing at extremely cold temperatures in special, expensive freezers. The initial vaccines also won’t be available for pregnant women and children younger than 12, who will need to be carefully studied and monitored before being cleared for vaccination. Kids 12 and older may receive vaccines before the fall 2021 school term, Moss said, though the youngest ones may have longer to wait.

Eventually, the most ideal vaccine will not require freezing, and will only require one dose. There also might be a candidate that emerges with a higher efficacy rate than what has been reported so far, and more data could potentially show whether some vaccines work better for certain populations than others.

Despite all the unknowns, Moss noted the “astonishing” progress made in vaccine research over just 12 months, which has produced products able to protect as many as 95% of all participants from contracting the coronavirus. But not enough time has elapsed to determine whether the vaccines have any long-term side effects, Moss said, or whether vaccines can prevent transmission.

“We’ll only know the short-term side effects,” he said.

Vaccine research, production and manufacturing have been coordinated under Operation Warp Speed, a partnership between federal agencies and private-sector biotech and pharmacology firms and academic centers.

Vaccine development usually takes several years, but the public health crisis has expedited the process, allowing for shortened windows of study and approval. This means trading off more data points for a potentially quicker abatement of the pandemic.

But vaccines won’t save lives if the majority of the public has doubts or refuses to get one, said Rupali J. Limaye, the director of behavioral and implementation science at Hopkins’ International Vaccine Access Center, during Thursday’s briefing.


States, in coordination with federal officials and drug companies, must begin identifying potential barriers to widespread vaccination — including the trust disparities between white and nonwhite populations. Officials also must communicate realistic expectations about the amount of time it will take to get enough people vaccinated and what side effects could surface.

For example, experts should be quick to notify participants if the vaccine they get can cause cold or flu-like symptoms such as nausea or headaches. And though the development timeline has been sped up, it will be federally vetted before it gets to the masses.

“There has to be messaging to address issues such as hesitancy, so that appropriate intervention can be applied,” said Limaye, an associate scientist in the Bloomberg School’s department of international health. “It must be tailored to meet different audiences and it must be credible and transparent.”

FDA officials will hold a public meeting next week to assess the vaccine data. Should one or more of the candidates be confirmed, Maryland will likely receive an initial rollout of about 155,000 doses, about half the volume needed to vaccinate the state’s “essential” health care workers, Gov. Larry Hogan said at a Tuesday news conference. The 155,000 includes only the first of the two doses needed, with a second set of doses to come later.

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Maryland health officials have developed a draft mass vaccination plan that officials say is still evolving. But it follows national guidance in putting the priority on front-line health care workers followed by those in nursing homes and first responders.

Hogan said the draft has been submitted to the U.S. Centers for Disease Control and Prevention.


Hogan said Thursday morning during an appearance on ABC’s “Good Morning America” that he hoped production would “really ramp up” under the Operation Warp Speed program so vaccination could accelerate.

“The question is just how fast can we get these vaccines out there to cover as many people as we can,” he said.

“Sadly, the darkest days are yet ahead ... the worst part of this virus is still coming in the weeks and maybe the month or two to come. And we’re not going to have enough [vaccines] for everybody, so we’re just asking for patience. The good news is the cavalry is on the way. There is a light at the end of the tunnel, but we’ve still got some pain to go through before we get this under control.”

Given the shortage, the governor said the state faced difficult decisions about vaccine distribution, such as whether health care workers should get all 155,000, or whether that should be distributed among Maryland’s most vulnerable residents.

As of Thursday, more than 1,500 patients were hospitalized in Maryland due to COVID-19 complications, according to state data. Nationwide, about 100,000 beds were occupied due to the virus, the most recorded since the outbreak began. More than a quarter of a million Americans have died due to the virus, with top infectious disease experts predicting even more to come in the weeks ahead.