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Does the coronavirus vaccine hurt? Are there side effects? A Japanese doctor explains

Doctor Kosuke Yasukawa receives the vaccine against the coronavirus at a hospital in Washington, U.S., on Jan. 5, 2021. (Photo courtesy of Kosuke Yasukawa)

TOKYO -- Coronavirus vaccinations started in Japan on Feb. 17. From its development to the inoculation method, the vaccine has numerous differences to shots commonly used in Japan for influenza and other conditions, which may have caused unease among some people.

    To find out a little more about the reality of receiving the vaccine, I interviewed Doctor Kosuke Yasukawa, 38, who works at a hospital in Washington, D.C., and was immunized with the vaccine from Pfizer Inc., a major U.S. pharmaceutical company, in December 2020 and January 2021.

    Mainichi (M): Why did you decide to get the vaccine?

    Kosuke Yasukawa (KY): Since March last year, I've been seeing patients with the coronavirus almost daily, and I'd always had a strong feeling of nervousness over whether I might get seriously ill, or pass the disease on to my colleagues, family, or patients. The results of the vaccine's clinical trials announced last December showed it was very effective, and I wanted to get vaccinated.

    M: Were you very worried about getting infected?

    KY: In the early days when it started to get around, I was. I saw hospitalized patients younger than me suffering from the spread of pneumonia. Several of my colleagues lost family members or relatives. However, as I treated patients with the coronavirus each day, I began to understand how to attend to them without getting infected, and gradually my anxiety diminished.

    M: When were you vaccinated?

    KY: On Dec. 16, 2020, and Jan. 5, 2021. I was vaccinated the day my hospital started giving shots to health care workers.

    M: In Japan, vaccinations are usually given subcutaneously, into the skin from a shallow angle, but the new coronavirus vaccine is given intramuscularly, deep into the muscle at an about 90-degree angle. Did you feel any pain from the needle?

    KY: I was inoculated in the deltoid muscle area of my left shoulder, but it was almost painless. Pain is easily felt on the skin's surface. Some people find hypodermic injections more painful because the way the needle stimulates the skin causes pain.

    M: What was your pain like after vaccination?

    KY: In my case, the pain at the site of the first vaccination started to worsen on the night of the day I had it, and the next day I couldn't raise my arms above my shoulders from pain. That lasted a few days. I had the same discomfort after the second vaccination. Many people may find the pain at the vaccination site more intense than from a flu shot. I think coronavirus vaccines tend to cause inflammation at the vaccination site due to the immune response.

    In clinical trials, 83% of those aged 55 and under and 71% of people aged 56 and older complained of pain at the vaccination site after the first shot was administered; after the second vaccination, the percentages were 78% and 66%, respectively.

    M: What other side effects did you have?

    KY: The day after the second inoculation, my body temperature rose to 37.2 degrees Celsius, and I had strong feelings of fatigue -- like catching a cold. I felt sluggish and didn't want to do anything until that night. Some of my colleagues also had fevers over 38 C, headaches and chills after the second vaccination, and could not sleep.

    It has been reported in clinical trials that these side effects are more likely after the second vaccination. For example, among people aged 55 and under, 4% had a fever after the first dose, while 16% had a fever after the second. But there are some vaccines that cause fevers reasonably frequently. For example, one shingles vaccine causes fevers in about 20% of people.

    M: So the vaccination may be disruptive to your work immediately after you have it?

    KY: Yes. For this reason, my hospital implemented a special paid leave policy for people who cannot come to work due to side effects in the 48 hours after vaccination. This should be taken into consideration in Japan, too. As you may experience arm pain and strong fatigue, you may want to adjust your schedule so that you can rest without straining yourself. I think it would be better to consider making it possible to take a day off if the side effects are painful, or to have the shot on Friday if you are off Saturday or Sunday, so you can rest as much as possible the day after vaccination.

    Also, taking antipyretic painkillers before vaccination to prevent pain is not recommended, as studies of other vaccines have shown it may weaken the immune response. But, you may take them if your symptoms after inoculation are severe.

    M: Did you have any anxiety about getting vaccinated?

    KY: I gathered information on the safety and efficacy of the vaccine from articles published in prominent medical journals and detailed reports by the U.S. Food and Drug Administration (FDA), which has the authority to approve vaccines for use, so I wasn't that worried. I was rather more eager to get vaccinated as soon as possible.

    According to published papers, the Pfizer vaccine is 95% effective in preventing the onset of the disease, which is very good. In addition, there have been very few serious side effects. I think a lot of people in Japan are concerned about side effects, so I hope many people can hear about this information.

    M: But, it's still not clear what kind of long-term side effects there may be?

    KY: While it is important to examine the possibility of long-term side effects, most of them occur within a short period of time, up to six weeks after vaccination. The most important side effects are down to immunity. Vaccines from Pfizer and (US biotech company) Moderna Inc. have been shown to cause a very rare systemic allergic reaction called anaphylactic shock. This is also a side effect of the immune system, mostly occurring within 30 minutes after vaccination, and it is treatable.

    I am often asked about uncertainty over what will happen a year or two on. However, considering that the messenger RNA (mRNA) used in both vaccines (which is an artificial replication of part of the new coronavirus's genes) is not incorporated into the DNA in the nucleus of human cells, and is instead broken down relatively quickly in the body, long-term side effects are considered very rare.

    M: What efforts are being made in the U.S. to reduce people's anxiety about vaccines?

    KY: To eliminate anxiety, it is important to properly inform people in advance of not only its effects but also its expected side effects. If you get the right information, I think there is little reason to be hesitant about this vaccine.

    In the U.S., when the FDA held an advisory committee meeting in December 2020 to hear expert opinions before approving the emergency use of the vaccine, the entire meeting was shown from morning to evening on YouTube to improve the discussion's transparency.

    In addition, the Centers for Disease Control and Prevention (CDC), which heads infectious disease control, publishes scientific and accurate information on its website. It answers people's concerns in a question-and-answer format that is very easy to read. It is very important that public institutions provide information answering questions like this.

    The media also has an important role. As far as I know, there are few major U.S. media outlets stoking anxiety or focusing only on side effects.

    M: How can we increase the vaccination rate in Japan?

    KY: It is very important to increase the general public's vaccination rate by upping the health care workers' rate. I don't think the people would want to receive vaccines that aren't administered by medical professionals.

    At my hospital, medical personnel are allowed to post pictures on social media of them being vaccinated. When the public sees so many doctors and nurses getting the shots, it may have be effective at increasing trust in vaccines.

    However, when something bad happens, like a fever or pain, some people may communicate that they wish they weren't vaccinated. I would like everyone to have enough knowledge that when they come into contact with information like that, they can look at it and think, "That's a side effect, which has a certain chance of occurring."

    M: Infection and death figures are lower in Japan than in Europe and the United States, so some people may think they don't need to be vaccinated. What do you say to this?

    KY: Even if that is the case, the number of infected people is to some extent rising in Japan. Some have died while recovering at home. There were times when municipalities where the positive testing rate exceeded 10%, so the actual number of infections is thought to be higher than reported. It's also expected that overseas traffic will eventually resume. The pandemic will continue, and the risk of infection will not disappear.

    In the U.S. alone, more than 25 million people have already been vaccinated, and we know that serious side effects are very rare. I think it is good to know this before making a decision. Personally, I believe that the elderly, who are at high risk of serious illness, and those living with them, do not have much cause to hesitate.

    M: Even so, I think there are some who may decide not to get vaccinated.

    KY: Deciding to get vaccinated is ultimately down to the individual, and is not mandatory. Even in the U.S., there is a survey showing that about 20% of people don't get vaccinated. It is important that people deciding not to get vaccinated aren't socially punished.

    What I am concerned about, however, is what kind of information the person bases their decision not to get vaccinated on. If it was based on obviously wrong information or inaccurate knowledge, I think it's a waste of a good vaccine. There are also risks involved in not getting inoculated. This is a difficult issue, because information that arouses anxiety attracts interest and spreads quickly, but we need to make efforts to convey knowledge in an easy-to-understand form so that people can get vaccinated as much as possible.

    (Japanese original by Yuki Ogawa, Lifestyle and Medical News Department)

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