About 90% of the elderly have completed two doses of the new coronavirus vaccine, and about two out of three people in the total population, Prime Minister Kishida said twice in early November. We are aiming to complete the vaccination.
On the other hand, in the United States and other countries where vaccination has progressed early, the effect will decline over time, and a third additional vaccination called "booster vaccination" has begun.
We have summarized the movements surrounding the third inoculation.
WHO “Third inoculation should be standardized”
WHO = World Health Organization Advisory Board should standardize three doses of new corona vaccines such as Pfizer, Moderna and AstraZeneca on October 11 for people with moderate to severe immunodeficiency I announced the view that it is.
People with moderate to severe immunodeficiency say that the two doses up to this point are not effective enough and are at high risk of becoming severe.
In addition, the US government has stated that the effectiveness of the new corona vaccine is likely to decline over time, and that people who have been vaccinated for a certain period of time will be given additional vaccinations.
Among them, the FDA = Food and Drug Administration announced in September that Pfizer's vaccine
was given to people aged 65 and over, people aged
18 and over with
a high risk of aggravation, and medical workers working in workplaces with a high risk of infection. On the other hand, we allowed additional inoculation.
It is said that people who have been inoculated for at least 6 months after the second inoculation will receive it, and the inoculation has already started.
In addition, on October 14, the FDA's expert committee will also give Moderna's vaccine a third dose to people over the age of 65 and those over the age of 18 who are at high risk of aggravation. Recommended to enable.
In Japan as well, the government has decided to compile an overall picture of measures to prepare for the next spread of infection early next month, and for vaccination, it is assumed that the third booster vaccination will start within the year, and the system and concrete measures will be taken. Schedule will be revealed.
Neutralizing antibody level rises again with booster vaccination
Behind the fact that additional inoculations have started or are being considered in each country, the level of neutralizing antibody that suppresses the action of the virus decreases as time passes after the completion of the two inoculations, which has the effect of preventing infection. Has been reported to be declining.
Vaccine makers, on the other hand, say that booster vaccinations will raise neutralizing antibody levels again.
According to Pfizer, the neutralizing antibody level one month after the booster inoculation
increased more than five times for
those aged
55 and under and more than
11 times for those aged 65 to 85
compared to one month after the second inoculation
. I am reporting.
Moderna also said that the level of neutralizing antibody 2 weeks after the booster vaccination increased about 42 times compared to 6 months to 8 months after the second vaccination.
AstraZeneca also reported that the neutralizing antibody titer increased after the booster inoculation, and each company said that the neutralizing antibody level increased by the third inoculation and the effect was further enhanced.
There is also a study that says "it is highly effective even if the antibody is reduced"
On the other hand, some studies have shown that even if the number of antibodies decreases, the effect of preventing hospitalization and aggravation is sufficiently high.
Last month, a group of researchers from universities across the United States published a weekly report on the CDC Centers for Disease Control and Prevention, analyzing the effects of vaccines in 21 hospitals in 18 states.
According to this, the effect of preventing hospitalization
is 91% from 2 weeks to 120 days after the completion of 2 inoculations with
Pfizer's vaccine,
77% after 121st day, and with
Moderna's vaccine
▼ 2 weeks later. It was as high as 93% up to 120 days after
the start
and
92% after the 121st day
.
Furthermore, in Japan, "breakthrough infection", in which infection is confirmed more than 2 weeks after two vaccinations, has been reported, but the risk of aggravation is low.
The National Center for Global Health and Medicine analyzed data on more than 3,400 people admitted to more than 600 medical institutions across the country, and found that even elderly people with breakthrough infections
were not treated in the intensive care unit. One-eighth of the people who
died
,
▼
one-
third
of the people
died,
and the risk of aggravation tended to be low.
Third inoculation Which vaccine to use
The idea of whether to use the same vaccine or a different vaccine for the third vaccination has not been established.
In the United States and the United Kingdom, clinical trials are being conducted in various combinations to determine which vaccine should be given to boost immunity by "booster inoculation", which is further inoculated by those who have completed the inoculation.
The National Institutes of Health in the United States last week vaccinated 458 adults who had been vaccinated with Pfizer, Moderna, and Johnson End Johnson with the same or another vaccine four months to six months later. We showed the intermediate results of clinical trials that investigated whether there was a difference in the amount of antibody.
According to this, if anyone who received any vaccine received the Pfizer or Moderna vaccine by booster vaccination, the value of neutralizing antibody against the conventional virus would be about 10 to 30 times higher after 2 weeks. , It is suggested that any vaccine enhances the immune response.
In addition, although the number of participants in the clinical trial was small, there were no concerns about safety, and the value of neutralizing antibody against the delta strain will be clarified in the future.
The third vaccination should be given to those at risk of aggravation first.
Professor Kazuhiro Tateda of Toho University, a member of the government's subcommittee on measures against the new coronavirus, should prioritize the inoculation of people who are at risk of becoming severe, and for those with low risk such as the younger generation. Regarding inoculation, we should wait for future research.
Professor Tateda of Toho University
"Breakthrough infections occur over time after inoculation, but there are reports that they continue to be effective in suppressing aggravation and death. However, in elderly people and people with immunodeficiency. If you have a breakthrough infection, it will become severe and die at a certain rate. Also, for medical staff, the risk of becoming severe may not be high, but to prevent infection to patients, 3 It is necessary to consider the second vaccination. We should think carefully about the priority and how to proceed with the vaccination while looking at the status of the vaccination and the results of future research in various countries around the world. "