Epidemic prevention faces a two-choice choice
Written by | Yan Xiaoliu
Source | "Medical Community" public account
The effectiveness of the COVID-19 vaccine is supported by up-to-date and robust real-world data.
On 22 March, the University of Hong Kong's Li Ka Shing School of Medicine held a press conference on "Forward-looking Planning after the Fifth Wave of the Epidemic in the Hong Kong Special Administrative Region" (hereinafter referred to as "Forward-looking Planning").
At the meeting, Dean Leung Cheuk-wai shared a set of vaccination data. The results showed that under the widespread spread of Theomikronean BA.2, regardless of age, 3 doses of inactivated (Koching "Kerraf") or mRNA (Fosun "Fubitai") new crown vaccines can effectively prevent severe illness or death, and the protection is more than 97%.
Image courtesy of Youtube HKUMed
2 to 3 doses, the protective power is significantly improved
Research from the University of Hong Kong's Li Ka Shing School of Medicine discussed the different degrees of illness, age groups and vaccination doses under the epidemic.
The mainstream vaccination in the HONG Kong SAR is the inactivated (Kerrett") vaccine and the mRNA (Fosun "Fu bi Thai") vaccine.
The results showed that regardless of which of the two was given, 3 doses provided excellent protection.
For 20-60 years old, after the third dose of mRNA vaccine, the protection against severe illness and death was 98.5% and 99.4%, respectively. If the 3rd dose of inactivated vaccine is given, the protection against severe disease is 98.5%. Anti-death data is insufficient.
For people over 60 years old, the third dose of mRNA vaccine has 98.0% and 98.1% protection against severe illness and death, respectively. If the vaccine is inactivated, the relevant protection is 97.9% and 98.3%.
In terms of preventing mild/common infections, 3 doses of mRNA or inactivated vaccines were given to 20-60 years old, and the protective power was 71.5% and 42.3%, respectively. For people over 60 years old, the relevant protective power was 71.6% and 50.7%, respectively.
If 2 doses are completed, the vaccine also has a good performance.
In terms of prevention of severe/critical illness:
2 doses of mRNA vaccine for 20-60 years of age can increase the protective power from 85% (1 dose) to 95.2% and the protective power of 2 doses of inactivated vaccine in this age group can increase from 60.9% (1 dose) to 91.7%.
In people over 60 years of age, 2 doses of mRNA vaccine or inactivated vaccine were given, and the protective power was 89.6% and 72.2%, respectively.
In terms of preventing deaths:
People aged 20-60 years received 2 doses of mRNA vaccine or inactivated vaccine, with 96.4% and 94% protection, respectively.
In people over the age of 60, after receiving 2 doses of mRNA vaccine or inactivated vaccine, the protective power was 92.3% and 77.4%.
Image courtesy of HKUMed
The study further compared the "relative vaccine efficacy" of 3 and 2 doses.
In the case of inactivated vaccination of 3:2 doses, for example, in people aged 20-60 years, the protection against severe diseases is increased by 81.8%. For people over 60 years of age, the effectiveness of severe illness/death increased by 92.5% and 92.6%.
This means that in the face of BA.2, which is both highly transmissible and immune-evasive, 3 doses of mRNA and inactivated vaccines are effective in preventing severe illness/death.
This also suggests that completing 3 doses of vaccination is a necessary means of responding to the Opmikharong outbreak. It can significantly reduce the case fatality rate, reduce the burden of disease, and reduce medical run.
The next step in epidemic prevention in the SAR: facing a choice between the two
Leung Cheuk-wai is also an expert adviser to the HKSAR Government. At the press conference on the 22nd, he focused on the "next step of epidemic prevention in the special zone".
He said that the SAR government and society should choose between the two options listed in the "Forward-looking Plan" by late April, whether to continue to "dynamically clear zero" or "move towards terroir (endemic epidemics)".
If you insist on "dynamic zeroing", you need to do national testing. This helps to identify a large number of "hidden patients" with transmission.
Liang Zhuowei said that the advantage of "dynamic zero clearance" is that it can return society to the state before the fifth wave of the epidemic. But one of the difficulties is that the best time for universal testing has passed. The best time is from the end of January to the beginning of February 2022, to do more than 3 rounds of full testing.
At the same time, it is necessary to consider the isolation of confirmed patients after "full testing", the quarantine of close contacts and sub-close contacts, and how to deal with some nucleic acid testing patients. In addition, it is also necessary to consider upgrading the inspection and quarantine of airports and epidemic prevention hotels to ensure that there is no leakage of water and avoid the recurrence of the "leakage" of epidemic prevention hotels and the outbreak of the epidemic.
Another option is "Towards terroir". This choice depends on a higher "mixed immunity".
"Mixed immunization" means that there are people in the population who have been vaccinated and people who have recovered from infection, who have immune protection to prevent (re-) infection with the virus, as well as to prevent hospitalization and death. The prerequisite is that enough people get enough 3 injections or at least 2 injections.
According to the University of Hong Kong School of Medicine model, as of March 20, about 60% of the population in the HKSAR, or 4.4 million people, have been infected with COVID-19, and the peak of the fifth round of the epidemic has passed. At the same time, vaccination has been continuously improved, and the current 1 injection vaccination rate for people over 12 years old has exceeded 90%, and those who have been given 2 doses account for more than 80% of the total population. This makes it possible to achieve "mixed immunity".
If you choose "towards terroir", the biggest epidemic prevention goal will focus on the "three reductions", that is, reducing severe illness, reducing deaths and reducing hospital loads, and ensuring that the number of hospital admissions does not exceed the carrying capacity of the hospital authority. To minimize mortality, the number of deaths should be reduced to zero as much as possible, "always the bed and so on, not the person waiting for the bed". Once there is a hint that the health care system will be overloaded, it is necessary to strengthen or tighten epidemic prevention measures.
"Which strategy to choose, there will be controversy, I have noticed. But scientifically, these two are just early and late. Scientists around the world almost agree that the new crown virus will remain in the human world for a long time, and the 6th wave of the epidemic cannot be avoided. Liang Zhuowei said that based on scientific and public health theories, under the circumstance that the epidemic situation is controllable, it may be safer to gradually "move towards terroir".
Photo caption: Under the epidemic situation, the people of the Hong Kong Special Administrative Region have experienced anti-epidemic fatigue, depression and anxiety. In January 2022, the depression rate of the SAR population reached 1/10. Anxiety symptom rates range from 13% to 14%. /HKUMed
According to the "Forward Planning" data, if there is no invasion of new variant strains and no large-scale rebound in the data, by April 21, the number of new daily additions in the HONG Kong SPECIAL Administrative Region will drop to 3 digits, that is, less than 1,000 people. At that time, the number of infections in the fifth round of the HKSAR was about 4.5 million, and the number of deaths was 8,383.
Leung Cheuk-wai stressed that his speech is not a choice for the SAR government, but hopes to make decisions as soon as possible, gather consensus in society, and make two major preparations in advance, including first, to increase the vaccination rate, encourage 3 doses of vaccination for those over 60 years old, and at least 90% for those over 70 years old; second, to ensure the effective supply of oral anti-coronavirus drugs. The data model shows that the coverage rate of oral anti-coronavirus drugs is 56%, and the number of daily hospital admissions is about 521, which is close to the upper limit of the medical system, and if the coverage rate is 80%, the number of hospitalizations is about 377 per day.
According to the "forward-looking plan", assuming that the SAR is fully opened from June 1, the peak period of the sixth wave of the epidemic may appear in the first week of early June, and it will remain for about two months. The cumulative number of infections in this round of the epidemic may reach 2.21 million, and the cumulative number of deaths is 1540.
"As long as there is a decision one day and the measures are slowly relaxed, there will be a new wave of the epidemic." Liang Zhuowei said.
bibliography:
[2] Updates on Modelling the Omicron Fifth Wave.youtube HKUMed.
Source: Medical community
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