Another new corona virus vaccination in the fall?

The Ministry of Health, Labor and Welfare has decided to start vaccination against the Omicron strain after mid-October.

When will I receive the booster vaccination?

Should I wait for a vaccine for the Omicron strain?

I asked an expert what to think.

Vaccine for Omicron strain after mid-October

A new vaccine for the Omicron strain will start after mid-October.

The Ministry of Health, Labor and Welfare decided on such a policy on August 8.

The target is all people who have completed up to the second vaccination.

Specifically, there are two types of new vaccines: a vaccine that corresponds to the Omicron strain ``BA. It contains.

It is a type called “bivalent (nika) vaccine”.

Those who have completed the 2nd dose will receive the 3rd dose, those who have completed the 3rd dose will receive the 4th dose, and those who have completed the 4th dose will receive the 5th dose.

What is the effectiveness of the Omicron strain vaccine?

Is it possible to expect an effect from a vaccine that responds to the Omicron strain?

The mRNA vaccine currently in use is made using the genetic information of the virus, which is called the ``wild strain,'' when the spread of the new coronavirus began two years ago.

When inoculated, a "spike protein" is produced in the body, and an antibody corresponding to this is produced to suppress the virus.

However, the new coronavirus is mutating one after another, and since the beginning of this year, the Omicron strains ``BA.1'' and ``BA.2'' have spread, and now ``BA.5'' occupies almost all of them. .

The shape of the "spike protein", the part of the virus targeted by the antibody, has changed, and the effectiveness of conventional vaccines in preventing infection and onset is lower than that of previous mutant viruses.

For this reason, it is thought that if the genetic information of the Omicron strain is used to recreate the vaccine, it will be more effective.

In Japan, Pfizer and Moderna applied to the Ministry of Health, Labor and Welfare on August 8 for approval of "BA.1" and a "bivalent vaccine" for conventional viruses, respectively, on August 8 and August 10, respectively.

According to Pfizer's announcement, in a clinical trial involving more than 1,200 people aged 56 and over, the neutralizing antibody value when used as the fourth vaccination was 1.56 times higher than when using the conventional vaccine. means that it has risen to

I don't think there were any safety issues.

In a paper published before it was peer-reviewed by a third party, Moderna reported that clinical trials conducted in the United States showed that the level of neutralizing antibodies when used as the fourth inoculation was a conventional vaccine. It is said that it has increased by 1.75 times compared to the case.

Adverse reactions were mostly mild to moderate, including 77% pain at the injection site, 55% malaise, and 44% headache.

"Need a vaccine for the Omicron strain, better than using the conventional type"

Tetsuo Nakayama, a specially appointed professor at Kitasato University who specializes in clinical virology and is familiar with vaccines, said, ``Various mutant viruses have emerged, and the Omicron strain has a very large number of mutations compared to previous mutant viruses. Since the characteristics of the virus have changed considerably, there are aspects that the conventional vaccine cannot handle, and I think that a vaccine for the Omicron strain will be necessary.It would be better than using a conventional vaccine.” pointing out.

'Vaccine update required'

Professor Hiroshi Nishiura of Kyoto University, who specializes in mathematical epidemiology, said that after the Ministry of Health, Labor and Welfare expert meeting on August 10, ``BA.5'', which now accounts for almost all of Japan, was infected with ``BA.1''. After pointing out that it is known to evade the immunity that is obtained from the vaccine, ``We can say that the new vaccine will be more effective than the conventional vaccine, but we should not expect too much. As long as the infection is expected to continue in the future, it is necessary to vaccinate people with a high risk of severe illness, such as the elderly, and updating the vaccine is essential."

"It's no less effective than the vaccines we've had so far."

Professor Masayuki Miyasaka of the Osaka University Immunology Frontier Research Center, who specializes in immunology, said, ``At first, I thought it would be good if we could create vaccines that correspond to each mutated virus, but the mutation of the Omicron strain is very different from the past. However, the virus is steadily accumulating mutations that escape our immunity.I don't think we can expect much from a vaccine that is stronger than ever.However, it will be less effective than the current vaccine. I don't think so," he said.

Vaccinate Now or Wait for Omicron Strain Vaccine

Should we wait for a new vaccine while we can see that the new vaccine will start in the fall?

In the current infection situation that updates the highest number of infected people in the past, whether people who have not been vaccinated for the third or fourth time should be vaccinated now.

According to the website of the prime minister's official residence, as of August 12,

approximately 102.56 million people, or 81% of the population, have completed two doses

of vaccination, and 63.6 of the population have completed the third dose. Approximately 80.55 million people,

▽ Approximately 17.78 million people have completed the fourth vaccination, which is being promoted for the elderly.

Vaccines should be given at a certain interval from the previous vaccination, but it has not yet been shown how long the interval between previous vaccinations should be taken for vaccinations in autumn and beyond. .

“If you can get vaccinated now, consider getting vaccinated early.”

Takaji Wakita, Director of the National Institute of Infectious Diseases, who also serves as the subcommittee of the Ministry of Health, Labor and Welfare's Immunization and Vaccine Subcommittee, said at a press conference after the Ministry of Health, Labor and Welfare's expert meeting on August 10, "A vaccine for the Omicron strain is available. Even if it is introduced in mid-October, it is still unclear whether the vaccination will be sufficient soon.The current vaccine has the effect of increasing the severity prevention effect against the Omicron strain, so If there is a situation where the third or fourth vaccination is possible, I think it is necessary to consider early vaccination."

"People who have not completed the third vaccination, a vaccine that can be used now"

Professor Nakayama of Kitasato University said, "Currently, the number of infected people is increasing and the number of seriously ill people is increasing, so those who have not completed the third vaccination should use the vaccine for the Omicron strain now instead of waiting. I want you to think about getting a vaccine that you can."

Also, regarding the fact that the US FDA = Food and Drug Administration is recommending the development of vaccines corresponding to `` BA.4 '' and `` BA.5 '', ``It will take several months to complete. But it is better to inoculate with the vaccine that will come out in the future."

"It's better to get the current vaccine when it's available."

Invited Professor Miyasaka of Osaka University also said, "I think it would be better to inoculate the current vaccine when it is possible. We know that the current vaccine will be effective if it is repeated a certain number of times. It corresponds to the mutant virus. The development of a new vaccine is a cat-and-mouse game, and I believe that it is important to inoculate what is currently available."

The effect of the 4th vaccine

In fact, many countries have reported that the fourth vaccination reduces the risk of hospitalization and death and is highly effective.

(* The figure shows that the lower the number, the higher the effect.)

On August 2, an Israeli research group published the fourth round of research targeting more than 29,000 medical workers in the medical journal "JAMA Network Open". We reported the results of the analysis of the inoculation results.

According to this, in January, when the Omicron strain was rapidly increasing, more than 5,300 people received the 4th vaccination, and after that, 368 people were confirmed to be infected, but 3 times. Of the more than 24,000 people, 4,802 were infected.

The percentage of infected people was 19.8% for those who received three doses, but it was lower at 6.9% for those who received four doses.

(* The figure shows that the higher the number, the higher the effect.)

In addition, the CDC = Center for Disease Control in the United States in July, when "BA.2" etc. was spreading in 10 states, mRNA vaccine We reported the results of investigating the effectiveness of the vaccine for each number of inoculations.

According to this, among people aged 50 and over, the effect of preventing hospitalization was 55% for those who had been 120 days or more after the third dose, and 80% for those who had been 7 days or more after the fourth dose.

The CDC says that ``boosts should be given as soon as they are appropriate.''

In Japan, in July, the Tokyo Metropolitan Institute of Medical Science announced data on the level of neutralizing antibodies in healthcare workers who received the fourth vaccination.

Analysis of people in their 60s and 70s showed that the neutralizing antibody value was 855 four months after the third vaccination, but increased to 3942 after the fourth vaccination. is.

After the third vaccination, the average level remained high, but there was a large variation, and it was said that everyone had a high level by receiving the fourth vaccination.

Professor Miyasaka of Osaka University said, ``Looking at the data from Tokyo, many people who received the third vaccination have high antibodies, and this condition has continued for months, but there are great individual differences. It is impossible to know which people have high antibodies and which have low ones without testing.In addition, even people with high antibody titers can still be infected with BA.5. "People with low levels are naturally at higher risk of infection. I think it would be better to get a fourth dose."

In addition, Professor Kazuhiro Tateda of Toho University, a member of the government's subcommittee on measures against the new coronavirus, said, ``The next epidemic may not be the Omicron strain. , Or those who have received the fourth vaccination ticket need to take action to suppress the current infection situation by inoculating as soon as possible.

Even the current vaccine is effective in preventing aggravation by repeating the number of times, and it is considered to be effective in preventing infection to a certain extent.

Experts in immunology, virology, and infectious disease all agree that we shouldn't get too hung up on the type of vaccine, but rather when it's possible.