COVID-19 VACCINES

June 16, 2021

Hokesen Letter, No 218 (English ver.), June 1, 2021
Health Care Center, Tokyo University of Foreign Studies
Yasuhiro Yamauchi, MD, PhD

Vaccination by a specific pathogen can induce our immunity system against the pathogenic microbes which cause infectious diseases through the immune system and also can strengthen our immune system. Vaccines are generated from the pathogenic microbes itself, such as live attenuated microbes, inactivated microbes, and some components of microbes which include microbes’ structural protein and mRNA containing genetic information. Previous vaccines used to administer some proteins of pathogens to create immunity, however, this new vaccine for COVID-19 consists of generated mRNA which encodes microbes’ structural proteins.

In general, the expected effects of vaccines are: ①prevention of infection, which prevents infection itself, ②prevention of disease onset, which prevents symptoms from appearing even if infected, ③prevention of severe disease, which prevents progression to severe disease, and ④effects of herd immunity, which prevents spread of infectious disease by establishing the major population immunity. At present, it is known that COVID-19 vaccine has「prevention of disease onset」 and 「prevention of aggravation」 effects. Although the effect of preventing infection has not been fully clarified, the possibility of preventing infection has recently been reported. Also, the effect of “herd immunity” is unclear.

Currently, there are two types of vaccines that are available and approved under the Immunization Law in Japan: Pfizer Inc. and Takeda Co. / Moderna Co. In large-scale clinical trials overseas, both vaccines have a preventive effect of about 95% with Pfizer's vaccine (inoculate twice every 3 weeks: 12 years old or older), and Takeda / Moderna's vaccine (inoculate twice every 4 weeks: 18 years old or older) is about 94%, and high efficacy has been confirmed.

Those who cannot receive the vaccination are those who have fever (usually 37.5℃ or higher), those who have a serious acute disease, those who have a history of severe hypersensitivity to the components of this vaccine, and those who are not suitable for vaccination. Furthermore, the following should pay attention; those who take treatment for anticoagulation, those who have thrombocytopenia or disorders of coagulation, those who have diagnosis of immunodeficiency, those who have congenital immunodeficiency in relatives, those who have underlying disease, including heart disease, kidney disease, liver disease, hematologic disease and development disorders, those who have previous suspicious allergic reaction within 2 days after administration of vaccines, those who have convulsion in the past, and those who have possibility of allergy for components of this vaccine.

It has been reported that side effects associated with vaccination include pain, fatigue, headache, muscle and arthralgia, and these side effects might be easier to occur, compared to other vaccinations, such as influenza vaccination. It is also said that there is a high possibility that a side reaction will occur the second shot rather than the first shot. Fever and pain caused by the vaccine can be treated by taking antipyretic analgesics when necessary, but if the symptoms are severe such as severe pain or high fever or if the symptoms persist for a long time, it is recommended to visit a doctor. It has also been reported that anaphylaxis (acute allergic reaction: sudden onset of cutaneous, digestive, and respiratory symptoms occurs, resulting in decreased blood pressure and decreased consciousness) occurs at a rare frequency,

Treatment (medicine injection, intravenous drip, oral administration, etc.) will be performed immediately at the vaccination site or medical institution.

Currently, vaccination for the elderly is progressing, but it is expected that vaccination for non-elderly people (other than elderly) will progress in the future. Please consider to take COVID-19 vaccination positively.

For vaccination against new coronavirus infection, please check "About new corona vaccine" https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/vaccine_00184.html of the Ministry of Health, Labor and Welfare, and information on vaccination. In particular, "Corona Vaccine Navigation" https://v-sys.mhlw.go.jp/ is also an easy-to-understand site, so please check it.

Also, Information on the COVID-19 vaccine can also be found on the Prime Minister's Office website "About the new corona vaccine" https://www.kantei.go.jp/jp/headline/kansensho/vaccine.html.

If you have any questions, please consult the Health Care Center, TUFS.