Coronavirus

What happens if you do not get a second covid-19 vaccine dose?

The five million people who have foregone their second vaccine dose have public health experts concerned... but what are the possible impacts?

What happens if you do not get a second covid-19 vaccine dose?
GUILLAUME SOUVANT AFP

Experts estimate that there are about five million people in the US who have gotten one vaccine dose and forgone or postponed their second. Public health experts are scrambling to identify these individuals and ensure that they get their second shot.

How effective are the Moderna and Pfizer vaccines in preventing a covid-19 infection after just the first dose?

After the first dose, researchers found that these vaccines may only provoke a mild immune response and could lead someone to develop a more severe case of covid-19. Other studies have shown that one dose may provide a sufficient level of protection to prevent infection in the short term, but the immunity weakens without the second dose. When both doses are administered these vaccines have shown that they are able to provide a strong immune response for a longer period of time.

According to the Mayo Clinic, a leader in medical research, the two doses create immunity in different ways. The first dose trains your body by introducing your immune system to the virus and the second kicks “the body's system into gear.” So, while, your body will be able to recognize the pathogen after the first dose, the odds of creating a greater immune response increase after the second dose. After the second dose, researchers also hypothesize that the process of creating antibodies will occur much quicker.

Preliminary findings from a few studies currently undergoing peer review show that with Pfizer’s vaccine, a robust immune response is possible after the first dose. While this is positive news, the length of time your body will be able to create that response is unknown. For this reason, and others, public health experts are in agreement that the second dose is necessary to maximize protection.

Another major question mark lies with how a single shot can protect against coronavirus variants that were not present in the US when the Pfizer and Moderna clinical trials were conducted. While some studies have shown that fully vaccinated individuals are effectively protected against the variants, no studies have been published looking at how the variants fair against individuals who have only received one dose.

Why are people skipping their second dose?

There are logistical hurdles vaccine manufacturers and government authorities have had to overcome in order to get the correct amount of second doses to distribution centers. The New York Times has reported that this process runs much more smoothly today, but even a few weeks ago many vaccine goers found it challenging to find a location with the correct second dose near them, and “possibly gave up.”

Additionally, there has been widespread reporting that the second dose tends to cause greater side effects which may have increased hesitancy. While feeling side effects may increase reluctance in getting a second dose, the CDC has released guidance saying that the symptoms should only last a few days. On the other hand, a severe case of covid-19 can lead to hospitalization, long-term health impacts such as organ damage or memory loss, and even death.