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Effectiveness of COVID-19 vaccine declining while myocarditis rising?
Several papers have been published recently, and many media have proposed that vaccine-induced immune protection is declining based on these papers, that is, immunity waning.
Many media and journals have titles like this. In fact, some of these papers have been discussed before in the pre-print version, and some of the findings have been seen before, or are expected. Some reports are suspected of being partial or making a fuss.
Is the effectiveness of Pfizer vaccines declining?
The first thing that attracted attention was a real-world study (based on no medical insurance data) commissioned by Pfizer and published in The Lancet.
The results of this study were previously disclosed when Pfizer applied for the enhancement needle, and Pfizer used it as the supporting evidence at the time.
The pre-printed version of this article was uploaded the day before the FDA expert meeting, which violates the convention that these review meeting materials need to be provided some time in advance to provide sufficient time for analysis.
In the end, the study did not receive much recognition. It’s not that its main conclusion is controversial. In fact, the main conclusion of this study is that over time, the vaccine’s ability to prevent mild illness or infection has declined, but its ability to prevent severe illness remains at a high level, similar to the one before the discovery. Many studies have seen it.
It was not recognized later because of problems with the details. First of all, its effectiveness in preventing mild illnesses or infections has declined very much, less than 50% in four or five months. This rate was directly questioned by an FDA expert at the time that the calculation model was problematic. Secondly, the study emphasized that Delta did not cause a decrease in effectiveness. The decrease was only due to time, because the effectiveness of non-Delta mutations also decreased by the same magnitude. This statement may still be controversial.
Delta’s gradual dominance of the mainstream overlaps with the gradual increase in vaccination time, and it is difficult to distinguish. Including those places in Israel, it has been suggested that Delta has an impact on the effectiveness of the vaccine, especially the prevention of infection. This has a certain basis in science.
Delta spreads faster, and it takes a short time to infect a person. This may cause the vaccine to induce human immune memory before it can be fully mobilized, and it shows a decline in the ability to prevent infection or mild illness. However, it takes time for the development of severe illness so that immune memory can be used, which can explain why the protection of severe illness has little effect.
These details do not affect its main conclusions. Of course, if you don’t pay much attention to these two detailed arguments, its main conclusion itself is not much new. The response to the media reports is also very interesting.
Some media reports have the title of Pfizer vaccine immunity waning, and some medical professional reports have the title of maintaining the effectiveness of preventing severe illness at 93%. In fact, these titles are fine, but they do have a different focus, which makes people feel different when they read them.
The complexity of vaccine effectiveness tracking
There is also a study published in the “New England Journal of Medicine”, which is a study by Qatar to observe changes in the effectiveness of Pfizer’s vaccine. The conclusion is similar, that is, in more than half a year, the protective effect of the vaccine against infection or mild illness has decreased, but the protection against severe illness has been maintained well.
However, in Qatar’s observations, one month after Pfizer’s vaccination, the highest peak of effectiveness was only 77% of the protection against infection.
This is relatively low in all observational studies. why? It is necessary to consider that the main local virus strain at that time was the beta strain, and the immune escape of beta was relatively serious, so the effectiveness of the vaccine may be low.
This also tells us that different research must pay attention to its research methods, research background and other details, otherwise it is easy to misunderstand.
In addition to these two studies, there is also an Italian news. As of August 29th, 29 million people in Italy had received two doses of mRNA vaccine, including Pfizer and Moderna. According to the tracking data of the Italian health department, in the general population, no decrease in the effectiveness of the vaccine in preventing infection was observed.
After 7 months, the effectiveness of the vaccine was maintained at 89%, the prevention of hospitalization was 96%, and the death was 99%.
However, in immunosuppressed people, the effectiveness of vaccination begins to decline after 28 days, and the degree of decline varies according to the specific immunosuppression situation.
For people with underlying diseases but not immunosuppressed, the effectiveness of infection prevention is 75% one month after vaccination, and it drops to 52% at 7 months.
For people over 80 years old and in nursing homes, the effectiveness has declined, but infection prevention remains above 80%.
This result in Italy is in contradiction with some CDC studies. First, it did not observe a decrease in the effectiveness of infection prevention. Even if there is a decline in some special populations, it is not the same as that observed in the United States.
The United States observes that the decline is significant at high age, and according to Italy, it is more obvious that there are underlying diseases. It’s a pity that it was not published as a paper, and it is not easy to confirm the details. But this kind of contradictory research just shows the complexity of real-world analysis of vaccine effectiveness.
One possibility is that Italy has maintained a relatively strict mask order and other measures for a long time. These may have caused discrepancies in the data from Israel and the United States. In fact, it is the difference in human behavior that affects the effectiveness of the vaccine we see.
We have previously shared that Pfizer conducted an analysis of the effectiveness of the population vaccinated before and after the phase III clinical trial under the requirements of the FDA, and found that the infection rate tracked after unblinding is much higher than the infection rate before unblinding.
There may be differences caused by changes in the background infection rate and changes in human behavior. These factors all exist in the real world, so these interference factors should also be considered when considering different studies.
What do you think about antibody decline?
Regarding the decline in immunity, the “New England Journal of Medicine” also published an Israeli antibody follow-up study, and found that within half a year of vaccination, antibodies and neutralizing antibodies decreased.
This is actually predictable. But the strength of this study is that it has a large number of personnel, which can be said to confirm the antibody decline curve previously observed.
For example, it observes that the total antibody decline curve is relatively stable. The neutralizing antibody declines rapidly at the beginning, and then becomes more stable. This is in line with previous studies that showed that B cells mature during 2-3 months of mRNA vaccination.
In this process, better antibodies are selected, and these antibodies have a better neutralizing ability. Therefore, although the total number has declined, the overall neutralization ability has slowed down.
Another important point is that due to the large number of people, the Israeli study can see the differences among different groups of people. For example, it is found that the elderly have lower neutralizing antibodies than the young.
Combined with the previous studies, it has been shown that the effectiveness of vaccines for the elderly has declined earlier. These results will be of guiding significance for epidemic prevention practices such as enhanced injections.
But there are also some findings that at least seem to be inexplicable now. For example, men have lower neutralizing antibodies than women, and then obese have more neutralizing antibodies. So far, I have not seen any studies that say that the protective effects of vaccines differ between men and women.
Basic diseases such as obesity only show that the protective effects of vaccines are not much different from the general population or are slightly lower. What is the matter with this higher neutralizing antibody? , And further verification is needed.
Moderna is restricted due to myocarditis?
In addition to tracking effectiveness, vaccines must also track safety. The risk data of mRNA vaccine myocarditis has recently been reported differently in various countries. Several countries in Northern Europe say they have seen a higher incidence of Myocarditis in Moderna than in Pfizer.
Canada has reached the same conclusion. However, the risk of myocarditis of the two vaccines in the CDC’s tracking has remained the same. The Nordic argument is that the second shot of Moderna myocarditis may be one in five thousand young men, and Pfizer is 1 in 27 thousand.
In the United States, it is speculated that it may be as high as one in five thousand young men. Both CDC and FDA have mentioned this statement in recent discussions about enhanced needles.
The data in this area need to be further clarified. Myocarditis is the most serious rare adverse reaction observed in mRNA vaccines except for allergies. The specific mechanism is completely unclear. The second shot is higher than the first shot.
With the start of vaccination of teenagers and children, the third shot will start. What is the incidence rate? It is related to confirming that the vaccine benefit is greater than the risk. Finland and Sweden like Northern Europe have suspended Moderna’s use for men under 30.
There were reports in Denmark that it was suspended, but later it was said that it did not stop. If the data is not clear, it is easy to cause confusion. This has some similarities with the aforementioned vaccine effectiveness tracking. Collecting data in reality will be disturbed by various factors, and a variety of potential disturbing factors should be considered when interpreting a result.
For many listeners, it may be very confusing to see these various contradictory statements. For example, whether a child should receive one or two mRNA vaccines is different in different countries.
Now these are all ongoing data tracking and analysis, and some conclusions will be clear cut.
For example, most people need to be vaccinated, but others may be more difficult to determine directly, such as children. The risk of severe illness is relatively low. Is a single shot sufficient for protection? Different countries have different infection rates and different risks, and the conclusions of the analysis will be different.
But in general, even if there are differences in specific conclusions, in most cases, when it comes to specific policy recommendations, each country prefers more stable or conservative choices under its own national conditions, so you don’t have to worry too much about these decisions. risk.
Kaiser Pfizer effectiveness: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)02183-8/fulltext
Israel antibody research: https://www.nejm.org/doi/full/10.1056/NEJMoa2114583?query=featured_home
Qatar Pfizer vaccine tracking: https://www.nejm.org/doi/full/10.1056/NEJMoa2114114?query=featured_home
Italy effectiveness tracking: https://whbl.com/2021/10/06/italy-says-mrna-covid-jab-effectiveness-stable-after-7-months-but-not-for-all/
(source:internet, reference only)