What happens if you skip the second dose of the COVID-19 vaccine?

Threat of mutation, spread
Virus Outbreak Britain Vaccine
Posted at 5:45 PM, Dec 14, 2020

SAN DIEGO (KGTV) — As Pfizer’s COVID-19 vaccine begins circulating, there is another big logistical challenge ahead: reminding people to get the second dose.

Both vaccines developed by Pfizer and Moderna require two doses spaced several weeks apart. People who get immunized often feel fatigue or soreness shortly after the shot and may experience fever, particularly after the second dose, according to clinical trial data.

Doctors say those immediate, short-term side effects are a positive sign the immune system is revving up production.

The side effects are similar to that of the shingles vaccine. But studies show about 20 percent of the people who get the shingles vaccine skip the second dose.

Experts say if that happens with the COVID vaccines, there could be consequences.

The worst-case-scenario is that skipping the second shot could allow the virus to spread and mutate, and potentially build resistance to the vaccines, according to Penn State University biologist David Kennedy.

That outcome is considered unlikely, but the World Health Organization announced Monday it detected a new variation of the virus in England, showing the virus is already mutating without the evolution pressure of a mass vaccine program.

“Does this make the virus more serious? Does it allow the virus to transmit more easily? Does it interfere with diagnostics? Would it interfere with vaccine effectiveness? These are questions. None of these questions have been addressed yet,” said Dr. Michael Ryan, director of the WHO Health Emergencies Program.

When administered in two doses, Pfizer’s vaccine is 95 percent effective at preventing COVID-19 symptoms. The FDA’s review showed the vaccine could be up to 52 percent effective after a single dose, but the data was limited.

“I think you could probably say you’re going to have short-lived but incomplete protection,” said vaccine expert Dr. Paul Offit. “Protection from disease but possibly not asymptomatic shedding.”

It remains unclear whether people who are fully immunized against the virus can still spread it to others asymptomatically but someone who is only partially immunized may be especially prone to silent spread, according to Offit.

When Americans roll up their sleeves to get the COVID-19 vaccine, they’ll get a 4 by 6 inch index card from the CDC noting which brand they got, the lot number, and when they’re due for the second shot.

People who get Pfizer’s vaccine need to get a second shot 21 days later. People who get Moderna’s need to wait 28 days for round two.

The CDC is encouraging people to photograph their card with their cell phone as a backup, because beyond the index card, the logistics of reminding people about their second dose will vary by state and healthcare provider.

In California’s draft vaccination plan from October, the state said it was exploring ways to "systematically text, email, and/or auto-call individuals when their second dose is needed." The California Department of Public Health did not immediately respond to a request for comment about its latest plans.

Much of the work may fall to the healthcare providers who administer the shots. Although the vaccine will be free for individuals, the government is paying providers $17 for every first dose they give and $28 for every second dose, a way to incentivize providers to keep close tabs on patients.

However, only about 25 percent of the nation’s vaccination providers have systems that can send automated reminders, according to L.J Tan, the chief strategy officer of the Immunization Action Coalition.