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The recent approval of additional vaccines is expected to accelerate the vaccination rollout in Japan.
The Health, Labor and Welfare Ministry on Friday approved COVID-19 vaccines developed by U.S. biotechnology firm Moderna Inc. and British drugmaker AstraZeneca PLC. The Pfizer-BioNTech vaccine was approved earlier and is already in use in Japan.
The government’s next task is to promote vaccinations effectively by taking advantage of the characteristics of each vaccine.
“The addition of the new vaccines will help establish a broader scheme for the rollout,” health minister Norihisa Tamura told reporters Thursday after the panel’s meeting.
The Moderna vaccine is similar to the Pfizer vaccine. Its main component is a genetic material called messenger RNA, or mRNA. Overseas clinical trials showed the Moderna vaccine had 94% efficacy in preventing the onset of COVID-19, the same level as the Pfizer vaccine.
The frequency of adverse events is also similar to Pfizer’s. Vaccination side effects include fever, pain at the inoculation site and fatigue, occuring more frequently after the second dose. These conditions are similar to those observed with Pfizer’s vaccine, although the incidence of anaphylaxis tends to be slightly lower with Moderna’s.
According to data from the U.S. Centers for Disease Control and Prevention and other sources, more than 110 million doses have been administered in the United States, while France and Germany have each administered more than 2.2 million doses. Given the small number of people involved in clinical trials in Japan, the government plans to conduct a post-vaccination health survey regarding all three vaccines, with the voluntary participation of 1 million vaccinated people.
The central government is expected to use the Moderna vaccine at its large-scale mass vaccination sites in Tokyo and Osaka, which will open Monday, and the other large-scale sites planned to be set up by prefectural governments.
Wider use of the Moderna vaccine will mean increasing the kinds of vaccines that municipalities have to handle, possibly causing confusion. In COVID-19 vaccinations in Japan, two doses of vaccines made by the same company must be administered. This is because the safety and efficacy of combining vaccines from two different companies have not been confirmed in clinical trials.
To prevent mistakes that could result from handling several kinds of vaccines at a single site, the health ministry plans for the time being to separate vaccination venues depending on the type of vaccine they use.
“There is a system to prevent problems. For example, stickers specifying the product name are put on vaccine vouchers. But in reality, unexpected mistakes, like giving two doses to the same person in one day, have still occurred,” Kazunori Oishi, head of the Toyama Institute of Health said. “It is necessary to establish a system to prevent further mistakes.”
Reuters AstraZeneca’s vaccine
AstraZeneca vector vaccine
The AstraZeneca vaccine is a vector vaccine that uses a harmless cold virus, to which a gene containing information for the COVID-19 spike protein has been added.
The vaccine has slightly lower efficacy, at 70%, than the other COVID-19 vaccines, but is still more effective than an influenza vaccine. The biggest advantage of the AstraZeneca vaccine is its storage temperature. It is the only one of the three approved vaccines in Japan that can be stored in a refrigerator.
However, there are reports in Europe that some vaccinated people have developed blood clots, paradoxically accompanied by a decrease in platelets.
The European Medicines Agency said in April that blood clots should be listed as a very rare side effect of the AstraZeneca vaccine. Most of the patients who had the clots were women aged under 60.
Britain recommended that people aged under 30 with no preexisting diseases should use other vaccines. Germany took a cautious stance by limiting vaccination with the AstraZeneca vaccine to people aged 60 or older, while France set the line at 55 or older. In Japan, the government will not immediately use the vaccine but will carefully study the situation while watching cases overseas.
“Scientific data suggest that the benefits of vaccinations are significant with all vaccines,” said Prof. Tetsuya Matsumoto of the International University of Health and Welfare. “The government must disseminate information on the differences in the types of vaccines thoroughly and help the public to get inoculated without confusion.”
The Yomiuri Shimbun A man rolls up his sleeve at a large-scale mass vaccination site in Chiyoda Ward, Tokyo, where the Moderna vaccine will be administered.
Effective for variants
Several experimental results have shown that the Moderna vaccine is effective against coronavirus variants, just like the Pfizer one.
A study published in April by Moderna and the U.S. National Institute of Allergy and Infectious Diseases found that the blood of people who received two doses of the Moderna vaccine contained more than 50 times the amount of antibodies needed to prevent transmission of the so-called British variants. Although the amount of antibodies effective against the British variants was smaller than the amount of antibodies effective against the conventional virus, the study concluded that the vaccine is sufficiently effective against the variants.
Earlier this month, Yokohama City University announced that more than 90% of the blood samples from 105 doctors who had been vaccinated with two doses of the Pfizer vaccine had sufficient antibodies against the so-called British, South African and Indian variants. The same was true for blood samples taken from 15 foreigners who had received two doses of the Moderna vaccine.
An analysis of 260,000 people who were vaccinated with the Pfizer vaccine in Qatar — where patients infected with the British and South African variants account for more than 90% of cases — found that infections with the British variants fell by 89% and those with South African variants dropped by 75%.
“It can be said the effects of the vaccines from the two companies [Pfizer and Moderna] on the variants is comparable,” Yokohama City University Prof. Takeharu Yamanaka, who specializes in clinical statistics, said. “I hope those vaccines will help control infections in Japan.”
The effectiveness of the AstraZeneca vaccine varies depending on the variants, with its effect against the British variant slightly less than its effect against the conventional virus. Clinical trials in South Africa reported the vaccine has 10% efficacy against the development of mild or moderate symptoms for those infected with the South African variants.
