Japan rolls out vaccines against Omicron

This article is part of a series on important coronavirus-related information. Click here to read other installments: #Coronavirus the facts. Find the latest information on everything COVID-19.

Bracing for a possible winter infection surge

Coronavirus vaccines that target the Omicron variant are available to people in Japan aged 12 or older who have already had the first series of two shots. For eligibility, five months must have passed since the last vaccination. The current rules stipulate that an eligible person can only get one Omicron-targeting shot.

Japan's health ministry aims to administer the Omicron vaccinations by the end of the year for everyone who wants to receive them. Officials are worried about a possible resurgence of infections during winter.

Medical workers, older people first

Medical workers and older people who have yet to receive their fourth shots are first in line. The number of people who are eligible for the shot will be expanded during mid-October. Local municipalities have been asked to deliver vaccination coupons by the end of October. Unused coupons originally meant for the third shot will also be accepted.

Pfizer and Moderna vaccines approved

The vaccines that have been approved for use in Japan are made by Pfizer and Moderna. They target both the initial coronavirus strain and the BA.1 Omicron subvariant. It is also expected they will be effective against the prevailing BA.5 type. The Pfizer vaccine is for people aged 12 and older, while the Moderna vaccine is for those 18 and above.

Neutralization antibody level

Pfizer says a clinical trial involving people aged 56 and older who received the vaccine as their fourth shot found that neutralization antibody levels for BA.1 increased by 1.56 times compared with previous vaccines. A similar trial by Moderna reported an increase of 1.75.

In terms of effectiveness against BA.5, Pfizer announced in June that the neutralization antibody level was one-third the protection the vaccine offers against BA.1 -- but that it effectively suppresses the activity of BA.5. Moderna reports its neutralization antibody level against BA.5 is 1.69 times compared with previous vaccines.

Side effects

Side effects are expected to be similar to those reported previously. Pfizer's clinical trial found 58.1 percent of people experienced localized pain around the injection site. Another 49.2 percent reported fatigue, 33.6 percent headache, and 5 percent had a fever of 38 degrees or more. Moderna's study reported 77.3 percent, 54.9 percent, 43.9 percent, and 4.4 percent for the equivalent symptoms.

Take whichever booster is available

Some people who are already booked to receive previous vaccines for their third or fourth shot are wondering if they should wait instead for the Omicron-targeting boosters.

Professor Saito Akihiko, pediatrician and pediatric infectious disease specialist at Niigata University, says while Omicron-targeting vaccines can be more effective, the basic rule is to receive the booster shot regardless of the vaccine type, as early as possible -- provided five months have passed since the last shot. He says it is uncertain when the next infection wave will arrive, so it is best to be prepared.

Large-scale vaccination centers

Starting from October 3, large-scale vaccination centers run by the Self-Defense Forces in Tokyo and Osaka will administer the Moderna vaccine. Vaccinations will be also available at workplaces and universities from the week starting October 24, with Moderna.

This information is accurate as of September 29, 2022.