When will the vaccine for Omicron start? What about side effects? What I have learned

On September 20, vaccination against the Omicron strain of the novel coronavirus began.

Which vaccine should I inoculate, “conventional” or “for Omicron strain”?

Will there be more "BA.5 compatible" vaccines in the future?

Simultaneous vaccination with influenza vaccine?

What about vaccinations for children?

I have summarized what I have learned.

What is Omicron Strain Vaccine?

The newly inoculated vaccine includes two types: the vaccine corresponding to the Omicron strain "BA.1" and the original vaccine that has been inoculated so far.

This type is called a bivalent vaccine.

The new coronavirus mutates repeatedly, and the shape of the "spike protein" on the surface of the virus, which is targeted by the antibody produced by the vaccine, changes.

With the Omicron strain, the effectiveness of conventional vaccines in preventing infection and onset has decreased, so a corresponding vaccine was created using the genetic information of the Omicron strain.

There are two types of vaccines for Omicron strains that have been approved for use in Japan.

Pfizer and Moderna's messenger RNA vaccine, as has been vaccinated so far.

We can compare whether or not this vaccine is expected to be effective based on how much the "neutralizing antibody" that suppresses the action of the virus, which is produced in the body by the vaccine, has increased.

According to the package insert of Pfizer's vaccine, when used as the 4th inoculation in a clinical trial targeting people aged 56 and over, the value of neutralizing antibody against "BA.1" was higher than that of the conventional vaccine. It means that it has increased by 1.56 times compared to .

The main adverse reactions were ▽ pain at the injection site 58.1%, ▽ fatigue (malaise) 49.2%, ▽ headache 33.6%, ▽ fever of 38 degrees or higher 5.0%, which often appeared the next day. It means that it often lasts for two days.

In addition, according to a paper published by Moderna in the medical journal "New England Journal of Medicine" on September 16, as a result of a clinical trial conducted in the United States, when used as the fourth inoculation, "BA.1 It is said that the neutralizing antibody value against ” has increased 1.75 times compared to using the conventional vaccine.

The main adverse reactions were 77.3% pain at the vaccination site, 54.9% malaise, 43.9% headache, and 4.4% fever of 38 degrees or higher, which is the same as the previous vaccines. Portions were mild to moderate.

Is it also effective for "BA.5"?

It is said that this vaccine for the Omicron strain can be expected to be effective against "BA.5", which is currently the mainstream of infection.

According to Pfizer's announcement in June this year, the level of neutralizing antibodies against "BA.5" was one-third that of "BA.1", but it effectively suppressed the action of the virus. increase.

In a clinical trial of Moderna, the neutralizing antibody value against "BA.5" was 1.69 times higher than that of the conventional vaccine.

What time do you vaccinate?

This vaccine is a "booster vaccine" used for the third and subsequent vaccinations.

Target of inoculation is all people 12 years or older who finish inoculation to the second.

According to the website of the prime minister's official residence, more than 80% of the population, including children, have been vaccinated for the second time.

Those who have completed 2 doses can be vaccinated as the 3rd dose, those who have completed the 3 doses as the 4th dose, and those who have completed the 4th dose as the 5th dose.

The interval from the last inoculation is 5 months.

It will start with the elderly and medical workers first, and local governments will expand the target population while monitoring the progress of vaccination.

Which vaccine should I get next?

Some of you may have already scheduled a conventional vaccine and had an appointment for a third or fourth dose.

Should I get an early booster with the conventional vaccine, or should I wait for the Omicron strain vaccine?

Professor Akihiko Saito of Niigata University, a pediatrician who is familiar with vaccines, said, "If there is an opportunity to inoculate a vaccine for the Omicron strain, I think that it will be more effective. The general rule is to get vaccinated as soon as possible, five months after the first vaccination.Because you never know when the next wave of infections will come, don't assume that the epidemic will come in winter. It is necessary to keep

On the other hand, Tetsuo Nakayama, a specially appointed professor at Kitasato University who specializes in clinical virology and is familiar with vaccines, said, "There is an option to inoculate with conventional strain vaccines, but vaccines containing ingredients for Omicron strains are more effective. Considering the risk of infection, it is basic to get vaccinated if it is possible to prevent it with a vaccine, but looking at the current infection situation, the number of new infections is decreasing, so you can spend your time paying attention to infection control. If so, waiting for a vaccine for the Omicron strain is also an option."

Need an early booster?

There are also reports that conventional vaccines become less effective against the Omicron strain within months, requiring early booster vaccinations.

A South African research group analyzed the effectiveness of Pfizer's conventional vaccine in preventing hospitalization in approximately 30,000 people.

(Published September 14 in The New England Journal of Medicine).

As a result, the effect of preventing hospitalization was 50% at the time of ``BA.1'' and 46.8% at the time of ``BA.5'' 3 to 4 months after 3 doses of vaccination. did.

The group concludes that the effectiveness of preventing hospitalization drops off sharply for the Omicron strain.

And it was shown that it was necessary to take additional vaccinations as early as four months after the last vaccination and introduce vaccines that correspond to mutant viruses.

Professor Nakayama said, ``Even in our research, when we test the blood of people who have been vaccinated so far, the immune function, such as antibodies, declines after about three months, and we wait until five or six months. Overseas, clinical trials are being conducted with a range of vaccination intervals, such as 3 to 6 months. I want you to take care of me,” he says.

A subcommittee of experts from the Ministry of Health, Labor and Welfare also expressed an opinion that the vaccination interval should be shortened from 5 months, and the Ministry of Health, Labor and Welfare will consider it in the future.

Should we wait for a BA.5 vaccine?

Meanwhile, on September 13, Pfizer applied to the Ministry of Health, Labor and Welfare for approval of a vaccine containing a component corresponding to "BA.5", which is the main infection of the Omicron strain.

Moderna plans to apply for a similar vaccine in the near future.

This vaccine is approved for emergency use in the United States.

Should we wait for a BA.5 vaccine?

Vaccines for "BA.5" may be highly effective against "BA.5", which is currently the mainstream, but it is not yet known when it will be approved in Japan.

In the UK and Canada, as in Japan, vaccination against "BA.1" has been decided.

Experts say that rather than waiting for a vaccine compatible with "BA.5", we should get a vaccine compatible with the Omicron strain "BA.1", which has been newly inoculated in Japan, or a conventional vaccine.

According to the Ministry of Health, Labor and Welfare, vaccines compatible with "BA.1" are more effective than conventional vaccines against Omicron strains. It is expected that it is likely to be effective even if

On top of that, I would like you to get a vaccine that corresponds to the Omicron strain that can be inoculated at that time, that is, a vaccine that corresponds to "BA.1".

Can't you hit the Omicron strain vaccine from the beginning?

The vaccine for the Omicron strain is to be used as a booster dose for those who have completed the first two doses.

Is it possible for people who have not received the first vaccination to be vaccinated against the Omicron strain from the beginning?

Professor Nakayama of Kitasato University said, ``The vaccine for the Omicron strain is approved as a booster vaccine on the condition that you have a good memory of immunity. It has not been done and there is no efficacy or safety data, so it may be difficult."

On the other hand, there are also opinions that should be considered in the future.

Professor Saito of Niigata University said, ``The vaccine for the Omicron strain contains the components of the conventional vaccine, so one strategy is to inoculate it from the beginning. should be considered in the future," he said.

However, Professor Saito said, ``Data on the efficacy and safety of vaccines are becoming available. The second vaccination is supposed to be until September 30, but I would like you to extend it and create an opportunity for vaccination."

What should children do?

Can children be vaccinated against the Omicron strain?

Vaccines for the Omicron strain can be administered to people over the age of 12, so junior high and high school students should be considered in the same way as adults.

However, children aged 5 to 11 are not eligible for this vaccine, and experts say they should consider getting the conventional vaccine instead of waiting for an Omicron strain vaccine for children. .

Professor Saito of Niigata University said, ``It will take some time before a vaccine for children against the Omicron strain is released. I'm talking to

More than 20% of children have completed the second vaccination.

On the other hand, since the highly contagious Omicron strain became mainstream, the number of children who become seriously ill and die is increasing.

The National Institute of Infectious Diseases analyzed 29 of the 41 children under the age of 20 who died after the outbreak of the Omicron strain between January and August, for whom detailed information could be investigated. , About half of the patients had no underlying disease.

Professor Nakayama of Kitasato University said, ``At first, there were opinions that children might not need a vaccine because they were asymptomatic or had mild symptoms even if they were infected, but there were people who were infected with Omicron. As the number of children with the disease increases, some children develop encephalopathy or even die.There are also cases of healthy children becoming severely ill.Vaccination will help prevent severe cases. "I'm talking.

Simultaneous vaccination with influenza vaccine?

This year, influenza spread in Australia in the southern hemisphere, where the season is opposite to Japan and the season for influenza is usually delayed by half a year from Japan.

It has been pointed out that there is a possibility that influenza and the new corona will be prevalent in the northern hemisphere at the same time.

Is it okay to get the new corona vaccine and the flu vaccine at the same time?

Overseas research groups have reported that there were no problems with safety or efficacy.

The CDC = Center for Disease Control and Prevention in the United States compared more than 92,000 people who received Pfizer and Moderna's new corona vaccine and influenza vaccine at the same time, and more than 889,000 people who received only a booster dose of the new corona vaccine. We reported the results in July.

When vaccinated at the same time, the rate of local symptoms such as pain at the vaccinated site is 1.10 times higher for the Pfizer vaccine than for the new corona alone, and 1.05 times higher for the Moderna vaccine. The rate of systemic symptoms was 1.08 times higher for the Pfizer vaccine and 1.11 times higher for the Moderna vaccine.

As a result of statistical analysis, although the rate of systemic symptoms was slightly higher in the case of simultaneous vaccination, there were no major safety issues.

In addition, according to a paper summarizing three clinical trials conducted in the United Kingdom and the United States in March this year by an Italian research group, the frequency of side reactions and the incidence of the new coronavirus There was no significant difference in antibody levels against

The Ministry of Health, Labor and Welfare has forecast that the supply of influenza vaccines for this year will be the largest ever, equivalent to about 70.42 million adults, and that simultaneous vaccination will not be a problem.

Saito, a professor at Niigata University, said, ``While we don't know when the next epidemic of the new corona will be, the influenza epidemic starts in November and December, and there is an annual pattern of peaking in January and February. It is important to thoroughly prevent the two infectious diseases."

Calm down and think in this declining situation

Even in Japan, the number of people infected with the new coronavirus has decreased significantly from the peak in August, when the number of people nationwide exceeded 200,000 per day.

Gradually, there is no doubt that the time is approaching when we will treat Corona as a normal disease and not as a pandemic.

However, many experts believe that the next "eighth wave" is coming.

WHO also says that it is important to continue measures such as vaccination in order to get closer to the 'end of the pandemic'.

Whether or not to vaccinate is a personal decision.

Many experts who have been working on countermeasures say that it is important to think calmly about vaccinations now that the number of infected people is decreasing.