The outlook seemed almost rosy when Dr. Joshua Schiffer and his colleagues set out to determine how factors like vaccination rate, vaccine effectiveness and social distancing might combine to bring the novel coronavirus pandemic under control.
“I was actually feeling pretty optimistic,” said Schiffer, an infectious disease physician and researcher at The Fred Hutchinson Cancer Research Center. His team’s mathematical modeling suggested that if the vaccine was rolled out quickly enough, there probably wouldn’t be a major fourth wave of infections in the spring and summer.
Then they factored in a new, more infectious variant of the virus and the picture changed significantly — for the worse.
Under almost every scenario they could envision, a fourth wave now appears likely.
But the model did zero in on the most effective tools to flatten the curve of coronavirus infections during that surge: a rapid pace of vaccination and a willingness to quickly impose restrictions when virus cases start to climb.
The findings confirm what public health experts have been saying for the past few months: Bringing the pandemic under control is now a race between vaccinations and the new variants.
“It seems we are right on the edge when considering whether a big next wave will happen,” Schiffer said. “We should definitely be vaccinating around the clock once supply allows.”
The only situation where a fourth wave might be avoided, according to the model, requires what seems like an unlikely confluence of conditions: a supercharged vaccination rate in excess of the Biden administration’s current target of 1.5 million shots a day; vaccines that remain highly effective, even against new variants; and governments and a populace willing to double down on masking and social distancing rules.
A one-dose vaccine, like Johnson & Johnson’s, could also be a game-changer if it’s approved soon for emergency use by the Food and Drug Administration, Schiffer added.
All models are hypothetical and uncertain, and Fred Hutch’s isn’t meant to make predictions about how the pandemic will unfold or how many people will die or become infected.
“I think there are just too many unknown variables at this point,” Schiffer said. “What we’re trying to say is: Here are the policy levers that would theoretically allow you to control this.”
The group’s preliminary results were posted on the preprint server medRxiv last week and have not yet been peer-reviewed.
But the prospect of a fourth wave propelled by new variants is something many scientists and modeling groups are warning about.
The U.S. Centers for Disease Control and Prevention (CDC) forecasts that the so-called U.K. variant, which is roughly 50% more transmissible, will outcompete the original strain of the virus and become dominant across the country by late March.
Almost 700 cases involving new strains have been diagnosed in 34 states, CDC Director Dr. Rochelle Walensky said in a briefing Monday. A new analysis of genetic sequences suggests infections caused by the variant are doubling every 10 days.
After revising its model to account for two new variants from the U.K. and South Africa, the Institute for Health Metrics and Evaluation at the University of Washington is forecasting an additional 200,000 deaths nationwide through June 1 — about 23,000 more than if the variants were not spreading rapidly. In Washington state, the forecast is for an additional 1,400 deaths.
Widespread mask use and maintaining social-distancing measures could reduce the U.S. death toll by 30,000, the model says — but many jurisdictions, including portions of Washington state, have been relaxing restrictions.
“What we’re seeing is sobering and will require us to continue taking this pandemic very seriously,” IHME director Dr. Christopher Murray said when announcing the new results on Jan. 29. “Getting vaccines out quickly is essential and masks are still one of the best tools we have to keep transmission low and avoid the worst possible outcome.”
The Hutch model focuses on King County but can be applied nationwide and to other states, Schiffer said. It assumes that the U.K. variant, which has been documented in five Washington infections, is present at low levels and spreading silently.
In all the modeled scenarios, the variant becomes the dominant strain by early summer.
One of the clearest findings in the new report is that delays in imposing what the modelers call “partial lockdowns” when cases start to spike could be dangerous.
“What’s clear is that if you wait a week or two, that’s a huge amount of time because of exponential growth,” Schiffer said.
One bright spot is that hospitalizations and death rates are likely to be lower during any fourth wave than in previous surges because many older people are getting vaccinated.
King County is currently administering about 10,000 vaccine shots a day. According to the model, that number may need to be increased by at least 60% to prevent a major summer spike in infections that could conceivably be larger than any previous wave.
Statewide, the current vaccination rate is about 28,000 per day. That’s still far short of Gov. Jay Inslee’s goal of 45,000 per day — and even that may not be enough to subdue the fourth wave, according to The Hutch analysis.
Rapid vaccination is also the best way to reduce the need for additional restrictions, Schiffer pointed out.
“It would absolutely be better to vaccinate more quickly than we are and we should shoot for it … when we have enough shots.”
At Monday’s White House coronavirus briefing, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, stressed that existing vaccines appear to be highly effective against the U.K. variant, though less so against the South African variant.
South Africa suspended use of the vaccine developed by AstraZeneca because of its poor performance against the new strain that predominates there and that appears able to dodge some antibodies.
“The hope is that we will get the virus under much better control by the time there’s any indication [the South African variant] might become dominant,” Fauci said. “It gets back to vaccinating as many people as you possibly can and implementing the public health measures.”