"Don't Forget Your Second Dose Even If the Vaccination Interval Has Passed"

[Image source=Yonhap News]

[Asia Economy Reporter Cho Hyun-ui] On the 18th, 51 days after the start of COVID-19 vaccination in South Korea, about 2.91% of the entire population had completed the first dose, while in the United States, voices are emerging that the second dose must be administered even if the vaccination interval has passed.

On the 17th (local time), The Washington Post (WP) stated, "To achieve the strongest and longest-lasting immunity when receiving messenger RNA (mRNA) vaccines such as Pfizer and Moderna, the second dose must be administered."

According to the U.S. Centers for Disease Control and Prevention (CDC), since the start of vaccination in the U.S., 3% of those who received the first dose of mRNA vaccines have not received the second dose.

An infectious disease expert in the U.S. emphasized to WP, "Skipping the second dose will make one more vulnerable to infection." He added, "Most people who were diagnosed with COVID-19 and hospitalized after vaccination had not received the second dose," and said, "I believe this carries significant meaning."

Last month, the CDC announced that a single dose of Pfizer or Moderna vaccines provides 80% preventive effectiveness. However, experts believe that "if the second dose is not administered, the 80% preventive effect will not be sustained and will decline." Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases (NIAID), also described this as a "weak 80%."

There are also research findings that variant viruses inhibit antibodies generated after the first dose. Experts said, "The second dose is a kind of booster shot," and "additional vaccination is necessary to strengthen vaccine effectiveness and maintain immunity."

WP cited experts saying, "However, if there are immediate side effects such as anaphylactic shock (acute severe allergic reaction), the second dose should be skipped." Nevertheless, they emphasized, "If there are simple symptoms like fever or body aches, the second dose should be administered."

What should be done if the second dose has already been skipped? Experts advise, "Even if the vaccination interval (21 days for Pfizer, 28 days for Moderna) has passed, the second dose should be administered immediately."

The CDC recommends completing the second dose within six weeks after the first dose, even if the scheduled date has passed. Experts also say, "Even if more than six weeks have passed, get the second dose regardless of the interval," and "It is not recommended to start over from the first dose."