First in the world: The Lancet China COVID-19 vaccine human trial data
This is the world's first official COVID-19 vaccine human clinical
trial results, and it is also the world's first show of adenovirus carrier
COVID-19 vaccine. The results are quite optimistic.
Previous discussions on the effectiveness of the COVID-19 vaccine focused on antibodies (humoral immunity), which may have caused the public to misunderstand that the effectiveness of the vaccine is only reflected in antibodies.
This study mentioned the importance of cellular immunity, and
then discussing the performance of vaccines, we should consider both antibodies
and cellular immunity.
Aadenovirus vector vaccine from Academician Chen Wei is safe, says The Lancet
In the middle of the night on May 22, the international authoritative medical journal "The Lancet" published online the results of the world's first human clinical trial of a COVID-19 vaccine, showing that the adenovirus vector vaccine from Academician Chen Wei is safe and can produce anti-COVID- 19 The double immune response of the virus.
Richard Horton, editor-in-chief of The Lancet, shared COVID-19 news through social media and praised:
The first human experiment results of
this COVID-19 vaccine found that it has good safety and tolerance, and can
Induce a rapid immune response. "These results represent an important
milestone."
The main results of the paper are as follows:
After the volunteers were vaccinated with this vaccine, enzyme-linked antibodies and neutralizing antibodies began to increase significantly from the 14th day of vaccination, and reached their peak on the 28th day after vaccination. The specific T cell response peaked on the 14th day after inoculation.
Among all 108 volunteers tested, 30 volunteers in the low-dose, middle-dose group, and 27 high-dose groups each reported adverse events within 7 days after vaccination. The most common ones are fever, fatigue, headache and muscle pain.
Among all reports, most were mild or moderate, and no serious adverse events were reported within 28 days after vaccination.
Academician Chen Wei said that these test results are an
important milestone. These test results show that a single dose of the
adenovirus vector vaccine can produce virus-specific antibodies and T cells
within 14 days, making the vaccine have the potential to be further studied.
However, Academician Chen also stated that these test results
should be interpreted with caution. The challenge of developing a COVD-19
vaccine is unprecedented, and the ability to trigger the aforementioned immune
response does not necessarily mean that the vaccine can protect people from
COVID-19.
Dr. Tao commented:
1. Unreserved disclosure of data
This paper published the safety and immune effect evidence of all 108 Phase I volunteers. In contrast, Modena disclosed 1/3 of the data on the website. The former is more rigorous than the latter.
2. The vaccine is safe
Although we saw that 2/3 of the volunteers reported adverse events, due to the lack of a placebo control group, it was actually impossible to determine whether these adverse events were caused by the vaccine.
These
post-vaccination health problems are only preventive adverse events (AEFI,
Adverse Event Following Immunization), rather than clearly causal adverse
reactions (AD, Adverse Reaction).
According to Dr. Tao’s experience, among these AEFIs, AD that
is really attributable to the vaccine may only account for 10% to 30%. A phase
II clinical trial with a control group can verify or beat Dr. Tao's
speculation.
3. First report of important cellular immunity
In the past, COVID-19 vaccine information disclosure usually only talked about antibodies, but in fact, antibodies are only one of the two major mechanisms of human immunity to microorganisms, which are usually called humoral immunity.
Another major mechanism is cellular immunity, which can
eliminate virus-infected cells. If these two mechanisms are compared to
weapons, then the humoral immune antibody is equivalent to a machine gun, which
kills directly and highly; cellular immunity is equivalent to heavy artillery,
which can destroy the city (cell) occupied by the virus.
Studies on people infected with SARS, MERS and COVID-19 found
that the increase in virus-specific antibodies is temporary and declines
rapidly after the patient recovers, while specific T cell responses play a
vital role in immunity .
It is reasonable to think that if the vaccine can induce humoral immunity and cellular immunity at the same time, then it is more likely to succeed.
Vector vaccines, mRNA vaccines and DNA vaccines are considered to
cause cellular immunity at the same time (this is an advantage). So the results
of cellular immunity will be observed, while inactivated vaccines usually
cannot cause cellular immunity, so cellular immunity observations are generally
not done during research.
4. It is not yet possible to determine effective antibody and cellular immune standards
Since the Phase I human clinical trial mainly observes safety
and there is no control group, it is impossible to determine the level of
effective antibodies and cellular immunity to achieve protection.
From the results of this study, the enzyme-linked antibody
against the RBD region of the virus S protein has a 4-fold growth rate of about
50% 14 days after vaccination, and more than 95% on 28 days.
More importantly, the 4-fold growth rate of neutralizing antibodies that directly fixes the virus is about 30% at 14 days and about 60% at 28 days. Dr. Tao thinks this result is not ideal, if it can be above 90%, it would be fine.
However, since the effective antibody standard has not been
determined, and cellular immunity is equally important, the result of the
4-fold growth rate of neutralizing antibody is not so attractive yet does not
explain the problem.
5. The optimistic results of animal experiments are disclosed
In the discussion section of the article, the performance of the vaccine in animal experiments is mentioned:
7 out of 8 ferrets vaccinated
withstand the virus attack, and the virus cannot be detected. Only among the 8
control ferrets not vaccinated 1 virus cannot be detected.
Dr. Tao hopes that the results of this animal experiment will
be published as soon as possible.
6. Human background adenovirus antibodies will affect the vaccine effect
Adenovirus itself is a common virus that causes the common
cold. Many people have certain adenovirus antibodies in their bodies, which may
affect the performance of adenovirus vector vaccines.
Studies have shown that before vaccination, 44% to 56% of the low, medium and high dose groups had high levels of background adenovirus antibodies (titer ≥ 1:200).
Their adenovirus antibodies increased by 4 times
after vaccination They are 25%, 37%, and 63%, respectively, which are
positively correlated with vaccine dose.
Multivariate analysis shows that if there are high levels of adenovirus antibodies before vaccination, the vaccine's COVID-19 virus neutralizing antibodies will be reduced, and it has nothing to do with the dose of the vaccine.
The older the age, the lower the level of COVID-19 virus
neutralizing antibodies.
In other words, people who often catch colds and older people have a weaker immune response to this vaccine.
However, whether this weaker immune response substantially affects the protective effect of the vaccine remains uncertain.
If this effect is confirmed in the future, it can be
resolved by adjusting the vaccine dose or increasing the number of
inoculations.
To Sum Up
This is the world's first official COVID-19 vaccine human clinical trial results, and it is also the world's first show of adenovirus carrier COVID-19 vaccine. The results are quite optimistic.
Previous discussions on the effectiveness of the COVID-19 vaccine focused on antibodies (humoral immunity), which may have caused the public to misunderstand that the effectiveness of the vaccine is only reflected in antibodies.
This study mentioned the importance of cellular immunity, and
then discussing the performance of vaccines, we should consider both antibodies
and cellular immunity.
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