You’re going to need more than one coronavirus vaccine. One dose of the vaccine is unlikely to be enough, experts say.


We’re all holding our breath for a coronavirus vaccine – for the day when everyone can queue up, get their shots, and then finally get back to life.

But there are a lot of issues with this vision, the first being: we’re all going to need more than one shot.

The research centers around the idea that anti-coronavirus antibodies dissipate after a period of several weeks or months. Although our immune system has more than a single line of defense, these results suggest that our immunity to the virus – whether generated in response to infection or as a result of a vaccine – may also be transient.

Because a vaccine’s effectiveness depends on its ability to trick the body to generate antibodies that protect you against future infection, it’s likely that people will need two doses of a coronavirus vaccine within a few weeks. interval for it to be effective.

Some experts suggest that then we will need to be revaccinated regularly.

“If the immunity proves to be fleeting,” disease ecologist Marm Kilpatrick told Business Insider, “we’ll need a vaccination plan plus a booster, or revaccination at regular intervals.”

Major drugmakers are already considering a 2-dose vaccination schedule

Countless vaccines, such as the one that protects against measles, mumps and rubella, require consecutive doses.

Some companies leading the coronavirus vaccine race are giving trial participants two injections three weeks apart. Pfizer is one of these: Early data showed that a two-dose regimen boosted the immune system response, with Pfizer researchers seeing the highest level of neutralizing antibodies a week after the second dose of participants.

Moderna’s clinical trial is to give participants two injections four weeks apart; The ongoing trial of AstraZeneca, on the other hand, tests the results of both a single dose of vaccine and two doses given one month apart.

coronavirus vaccine injection trial shot on patient covid 19

First patient enrolled in Pfizer’s coronavirus vaccine clinical trial at the University of Maryland, Baltimore School of Medicine, receives an injection, May 4, 2020.

University of Maryland School of Medicine / AP Photo

“It will probably be a two-round vaccine, which is not the end of the world. But it would certainly be much more practical if it was a single dose, ”Christopher Gill, an infectious disease researcher, told WBUR.

But it might be difficult for health systems around the world to make sure people come back for that critical second dose.

For example, research shows that less than a third of young women who choose to receive the first human papillomavirus (HPV) vaccine – which primarily targets viruses rather than cervical cancer – return for the two remaining doses to complete the series.

In addition, a double dose vaccine also requires twice as many vials, syringes, clinic visits, etc. at a time when these resources are already limited.

Then we might need reminders

After this initial vaccination, whether it is one or two doses, regular booster injections may also be necessary.

Some viruses, like hepatitis A or measles, are a one-off: once you’re infected (or inoculated), you’re immune for life.

“For human coronaviruses, this is not the case,” Florian Krammer, a vaccinologist at Icahn School of Medicine in Mount Sinai, previously told Business Insider. “You can be infected multiple times once your immunity wanes. “

A tube with a solution containing COVID-19 antibodies.

A tube with a solution containing COVID-19 antibodies.

Thomas Peter / Reuters

Scientists have not been able to study the new coronavirus long enough to determine the duration of immunity, and there is no clinical evidence yet that anyone has been re-infected. But people can repeatedly catch other human coronaviruses (the ones that cause the common cold).

“After infection with coronaviruses, reinfection with the same virus – although usually mild and only occurring in a fraction of people – is possible after a period of several months or years,” according to the Mayo Clinic.

But that’s not a problem if people become susceptible to re-infection sometime after the initial shot, Krammer said.

“This happens for a lot of vaccines,” he said. ” This is not a problem. You can get revaccinated. ”

This is what reminders are for. Your tetanus vaccine, for example, requires a booster every ten years. The question is whether follow-up coronavirus vaccines will be needed on a scale of months or years.

Work development of coronavirus covid 19 vaccine Great Britain.JPG

Scientists are working on a potential vaccine against COVID-19 in Keele, England.

Carl Recine / Reuters

According to Walt Orenstein, a vaccinologist and former director of the US National Immunization Program, experts won’t know if boosters will be part of the protocol until the vaccine is deployed.

“Once we start to see vaccine failures increasing, then we can look at booster doses. But we don’t know at this point if it will be necessary, ”he told Business Insider.

But if it turns out that people need to be revaccinated regularly, it decreases the likelihood that people will receive the vaccines they need to stay protected.

“The more complicated the schedule, the harder it is to get people to come,” Oreinstein said.

National and local authorities should start educating Americans now about the importance of getting the required vaccine doses, he added.

“Vaccines don’t save lives, vaccinations save lives. The doses of vaccine that are left in the vials are 100% ineffective, ”he said.

Andy Dunn and Hilary Brueck contributed reporting for this story.

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