COVID-19 vaccine FAQ


This page contains FAQs from Keio University residents.

About Coronavirus Disease 2019 (COVID-19)

1. About the vaccine

Can I still get COVID-19 after being fully vaccinated?▼
The vaccine does not give you 100% protection.
However, it's been reported that the vaccine can prevent around 94% of the symptoms if infected.
After getting the second shot, it takes around 14 days until sufficient immune response is established. Since you could still get COVID-19 and spread the virus even after getting vaccinated (though without symptoms), please keep following all preventative measures (wear a mask, wash your hands often, avoid crowds, and stay away from others).

How long does the immunity to COVID-19 last after getting the vaccine?▼
Since clinical trial for COVID-19 vaccines started last summer, we do not have the information at the moment. It is said that people who were vaccinated kept neutralizing antibodies in their blood for around 6 months according to the phase III trial data provided by Moderna. However, we do not know how long the immunity lasts. We still do not have any medical consensus regarding if any or when additional shot(s) are required.
Any updates will be uploaded to the Ministry of Health, Labour and Welfare COVID-19 Vaccine Website .

2. About side effects

What are the possible side effects of getting a COVID-19 vaccine?▼
Common side effects include pain on the arm where you got the shot*, headache, joint pain, muscle pain, tiredness, chills, fever. As this is a new type of vaccine, unknown symptoms could occur.
*More people feel the pain on the next day, rather than right after getting the shot. Pain and swelling could occur after a week or so.
Also, in the rare cases, people could experience severe allergic reactions including, anaphylactic shock.

Possible Side Effects After Getting a COVID-19 Vaccine(CDC)

3. Eligible person for vaccination

I recently got other vaccines. Is it ok if I get a COVID-19 vaccine soon after?▼
As the Centers for Disease Control and Prevention (CDC) of the U.S.A. previously recommended, the Ministry of Health, Labour and Welfare of Japan recommends that there should be an interval of 14 days before or after administration of any other vaccines.
The CDC's latest opinion is that COVID-19 vaccines and other vaccines may be administered without regard to timing; however, please follow the directions of the Ministry of Health, Labour and Welfare while in Japan.

Is it safe to get a COVID-19 vaccine while pregnant or breastfeeding?▼
Women who are pregnant and women who are breastfeeding are eligible to receive the COVID-19 vaccine. If you are infected with COVID-19 during pregnancy and do not have underlying medical conditions, the course of your illness is considered to be the same as women of the same age who are not pregnant. However, it has been reported that when infected during late pregnancy, the incidence of premature birth increases and some infected women themselves become severely ill.
There are no reports that the COVID-19 vaccines approved in Japan have adverse effects on pregnancy outcome, fetal growth, breast milk production and secretion, or female reproduction system. Therefore, we recommend vaccination based on the Immunization Act.
Please also check the reports published by the Japan Society for Infectious Diseases in Obstetrics and Gynecology, Japan Association of Obstetricians and Gynecologists, and Japan Society of Obstetrics and Gynecology. description only)
COVID-19 Vaccines While Pregnant or Breastfeeding(CDC)

I have underlying medical conditions. Will I be able to get vaccinated? Whom should I consult regarding any other concerns about my health and getting vaccines?▼
Please visit the web page below to see "who should not get vaccinated" or "who should take extra care to get vaccinated":
Moderna COVID-19 Vaccine Questions(CDC)

Certain underlying medical conditions can put people at increased risk for severe COVID-19 associated illness. Therefore, if you haven't had any allergies in the past, we recommend that you get vaccinated.
At the moment, we do not know any medication you should avoid when getting vaccinated; however, if you have any underlying medical conditions and have any concerns, please consult your doctor.

I have had an allergic reaction (including beestings) or anaphylaxis in the past. Is it okay for me to get vaccinated?▼
The presence of food allergies, bronchial asthma, atopic dermatitis (atopic eczema), allergic rhinitis and hay fever, hives or urticaria, or an allergic constitution do not alone preclude a person from getting vaccinated. In addition, those who have allergies to things unrelated to the components of the COVID-19 vaccine that will be used may also receive the inoculation. However, if you have experienced severe allergic reactions, including anaphylaxis, caused by a particular medicine or foodstuff,you are advised to wait at the vaccination venue for 30 minutes (longer than the standard 15 minutes) in order to act swiftly if you feel unwell immediately after receiving the vaccine.In addition, the US CDC does not recommend that persons who have experienced severe allergic reactions to a COVID-19 vaccine (including the first dose), such as anaphylaxis, or those who have had severe allergic reactions to polyethylene glycol (PEG) , a component of the vaccine, undergo the inoculation.

4. About health condition after vaccination

Will it be all right to take the over the counter pain relief medication for side effects (pain or fever) after vaccination?▼
While it may be advisable to use over-the-counter antipyretic analgesics (fever reducer and painkiller)* to counteract fever and pain following the administration of a vaccine dose, please consult with your primary physician or a pharmacist in the following cases.

・If you are taking other medications or are pregnant, breastfeeding, elderly, or undergoing treatment for conditions such as gastric/duodenal ulcers or renal dysfunction (there may be limits on the type of medicines you can take).
・If you have had allergic reactions or asthma caused by medicines
・If your symptoms are severe, including extreme pain or high fever, or if your symptoms persist over an extended period.
・If you have symptoms atypical to those generally experienced following vaccination (see here for the symptoms that are likely or unlikely to occur following the vaccination)

It is currently not recommended to repeatedly take antipyretic analgesics on a preventative basis after the vaccination but before any symptoms have manifested.

*Commercially-available antipyretic analgesics include acetaminophen and non-steroidal anti-inflammatory medicines (Ibuprofen, Loxoprofen, etc.), which can be used to counteract fever and pain following the administration of a vaccine dose. (Although acetaminophen may be used by younger individuals and pregnant or breastfeeding women, the target age, etc., differs by product. Please ensure that you have checked the targeted age group, etc., before taking.)

What should I do when I have swelling, pain or itchiness on the arm I got shot?▼
According to the survey result of CDC (Center of Disease Control and Prevention), 71% may feel side effects of pain on the injection part after the first dose of the Moderna COVID-19 vaccine. To reduce pain and discomfort, apply a clean, cool wet washcloth over the area. If you feel strong pain, take pain relief medication. If you fell itchiness, apply a clean, cool wet washcloth over the area or use antihistamine. If it does not get well in few days, consult the nearest medical institution.

Can I do work-outs after vaccination?▼
Please avoid hard work-outs on the day of vaccination.

Can I take a bath on the day I get the vaccination?▼
Yes, you will be able to take a bath on the day of vaccination.

I have been vaccinated within 48 hours and have fever, pain, headache, tiredness and muscle pain.▼
This may be side effects caused by vaccination. In that case, take pain relief medication (Calonal, Tylenol, Acetominophen). 24 hours consultation will be available at your nearest local side effect center.
◆Tokyo (東京都新型コロナウイルスワクチン副反応相談センター) Tel: 03(6258)5802
※English, Chinese, Korean, Vietnamese, Dagalog, Nepali, Burmese (Myanmar), Thai, French, Spanish, Portuguese available
◆Saitama (埼玉県新型コロナワクチン専門相談窓口) Tel: 0570(033)226
◆Kanagawa (神奈川県新型コロナワクチン接種後の副反応等に関する専門相談センター) Tel: 045(285)0719
◆Chiba (千葉県新型コロナワクチン副反応等相談センター) Tel: 03(6412)9326
If you have severe symptoms, see a doctor at your nearest medical institution.

It has passed 48 hours after vaccination and I have fever, pain, headache, tiredness and muscle pain.▼
There may be a possibility that you have been infected to COVID-19 by getting vaccinated during the incubation period. Please consult your nearest Fever Consultation Center.

Please also report to the Keio University Health Center by completing the online form on the following website:
※Staff of Keio University Hospital and Shinanomachi Campus, and students of School Medicine 2-6th year and Graduate School of Medicine.:
If you are getting in touch for the first time, please do so by telephone rather than via this form and follow the instructions from Shinanomachi branch of the Keio University Health Center (TEL 03-5363-3634).

What should I do if I feel any discomfort (without fever but have tiredness) after 48 hours of vaccination?▼
You may have some side effects, which are normal signs that your body is building protection.
Please consult your local side effect center or the Keio University Health Center on your main campus. If your side effects are worrying you, see a doctor at the nearest medical institution.