Source 丨21 Healthnews21 original work
Author 丨 Wei laughs
Editor 丨 Xu Xu
Picture 丨 Figure Worm
Recently, a study published in the CcDC Weekly analyzed the real-world protective efficacy of domestic vaccines (including inactivated vaccines, adenovirus vaccines, and recombinant subunit vaccines) against Delta and Omilon.
The study pointed out that compared with the international mRNA and adenovirus vector vaccines, there are fewer real research data on breakthrough cases in the domestic COVID-19 vaccination population. The analysis of clinical outcomes of breakthrough cases will be an important supplement to the efficacy and observational effectiveness data of domestic COVID-19 vaccine clinical trials.
The study used national COVID-19 surveillance and vaccination data from May 21, 2021 to February 28, 2022 to estimate the effectiveness of vaccines produced in China that are building population immunity to SARS-CoV-2 and its variants.
Studies have shown that COVID-19 vaccines produced using different technology platforms have a good effect in preventing serious illness and death, but less effective in preventing infections. The findings support that people aged 3 years and older without contraindications should be fully vaccinated against COVID-19, eligible adults should be given booster injections, and the vaccination of booster injections should be accelerated, especially among the elderly.
On April 19, according to the press conference of the joint prevention and control mechanism of the State Council, as of April 18, the cumulative number of vaccinations against the new crown virus was 3.317463 million doses, the total number of vaccinations was 1.282.12 million, and 1.246769 million people had been vaccinated, covering 90.94% and 88.43% of the total population of the country, respectively. 732.659 million people were immunized intensively, of which 25.426 million were continuously immunized. The vaccination of the elderly over the age of 60 has reached 225.521 million, and the whole process of vaccination has reached 213.938 million, and the number of people covered and the number of people vaccinated throughout the whole process account for 85.41% and 81.03% of the elderly population, respectively. Immunization enhancements have been completed for 154.874 million people.
The risk of severe illness in the elderly remains high in the Omikejon
The study is based on all confirmed COVID-19 cases Chinese mainland between 21 May 2021 and 28 February 2022.
During this period, the main variant in China changed from Delta to Omicron, assessing the protective power of the vaccine by comparing the proportion of patients with different severities in the unvaccinated, partially vaccinated, fully vaccinated and boosted subgroups.
Unvaccinated people include those who have not received any COVID-19 vaccines before infection or who have been vaccinated on the day of infection. Some vaccination groups consisted of individuals who had not completed their initial vaccination or had completed their initial vaccination less than 14 days before infection. The intact vaccination group consists of individuals who have completed 2 doses of inactivated vaccine 1 dose of adenovirus vector vaccine or 3 doses of recombinant subunit vaccination in 14 days or more prior to infection and have shifted their focus from infection prevention to prevention of serious illness and death vaccines. The booster dose group consists of individuals who received a booster dose 7 days or more before infection. Breakthrough cases are individuals who have completed full or enhanced vaccination before becoming infected.
According to the Novel Coronavirus Pneumonia Prevention and Control Plan (8th Edition) (2), cases are classified as asymptomatic, mild, moderate, severe or severe according to clinical symptoms. The researchers divided the severity of the case into two types, one is pneumonia, including moderate (that is, common disease), severe and critical illness, and the other is severe, including severe and critical.
During the study period, Chinese mainland reported a cumulative total of 10,829 confirmed cases of COVID-19, of which 8,675 were caused by Delta and 2,154 by Omikeron. Of the cases aged ≥3 years, 15.1% were unvaccinated, 7.3% partially vaccinated, 63.6% fully vaccinated, and 14.0% received booster doses.
Age-specific COVID-19 vaccination status in Delta and Omiljung infection cases in China from 21 May 2021 to 28 February 2022 Source: CCDC Weekly
Of the fully vaccinated cases, 95.1% (n=7849) received inactivated vaccine, 2.2% (n=183) received adenovirus vector vaccine, and 2.7% (n=23) received recombinant subunit vaccine.
In fully vaccinated Delta cases, the proportions of inactivated vaccines, adenoviral vector vaccines, and recombinant subunit vaccines were 95.9% (n=3197), 1.5% (n=50) and 2.6% (n=85), respectively, compared with 97.5% (n=157), 0 (n=0) and 2.5% (n=4) in severe cases, respectively.
In the fully vaccinated Cases of Omilon, the proportion of inactivated vaccines, adenoviral vector vaccines, and recombinant subunit vaccines was 90.9% (n=497), 6.2% (n=34), and 2.9% (n=16), respectively, with only 9 severe patients.
It should be noted that this part of the data cannot directly compare the protective efficacy of the three types of vaccines, because the mainland population is mainly vaccinated with inactivated vaccines, and the proportion of breakthrough infections of inactivated vaccines is of course higher than that of the other two types of vaccines. Secondly, the proportion of patients who are fully vaccinated is basically not much different from that of unvaccinated, which shows that in the face of delta and Olmi kerong, which are highly contagious and highly immune-evasive variants, the focus of vaccination has shifted from preventing infection to preventing severe illness and death.
Omikeron is more "mild" than Delta, but the risk of severe illness in older adults remains higher. Of the 1793 unvaccinated cases (1631 Delta and 162 Ormicron), the proportion of Delta cases developing pneumonia and severe illness was 59.0% and 10.6%, respectively, while the Numberon cases fell to 37.7% and 2.5%.
Overall, the likelihood of pneumonia in the case of Omikerong is 68% lower and the likelihood of serious illness is 80% lower. This shows that Omiquerong is indeed more "mild" than Delta, but the 37.7% of pneumonia and 2.5% of severe illness rates can not be ignored, especially ≥ 60-year-olds, the rate of pneumonia and severe illness of Omiljung is still as high as 79.5% and 28.3%.
How effective are domestic vaccines in preventing pneumonia and severe disease?
The proportion of pneumonia and severe illness in Delta cases is higher, but vaccination with domestic vaccines can significantly reduce the risk of pneumonia and severe illness. Take, for example, the Delta case is a population aged 18 to 59 years. Pneumonia developed in 363 (72.6%) of the 500 unvaccinated patients and 2392 (56.5%) of the 4233 patients who were fully vaccinated, with a P-value of <0.01.
Taking the unvaccinated group as a reference, the odds ratio of full vaccination was calculated to be 0.49, and it can be considered that full vaccination reduces the risk of pneumonia caused by Delta by 51%.
After vaccination with the booster needle, the odds ratio was 0.14, that is, the risk of pneumonia reduction reached 86% for strengthening. In the prevention of severe diseases, the risk of reduced full and intensive vaccination reached 83% and 98%, respectively.
But for Omikeron, the protection of vaccines has dropped dramatically. In the 18-59 age group, there was no significant difference in the proportion of pneumonia prevention and severe illness, whether full or intensively vaccinated, but for people over 60 years of age, the proportion of pneumonia caused by Omilon decreased from 79% of the unvaccinated group to 52% of the fully vaccinated group, and the incidence of severe disease decreased from 10.3% to 3.9%, although no significant statistical difference was achieved.
However, when older adults over the age of 60 are vaccinated with booster injections, the risk of pneumonia in Omikerong cases can be significantly reduced by 65% (OR 0.35) and the risk of severe illness by 90% (HR 0.9).
It can be seen that full vaccination or intensification of domestic vaccination has a good effect on reducing the risk of pneumonia and severe illness in the elderly.
Overall, the study shows that full and enhanced vaccination against domestic COVID-19 vaccines significantly reduces the risk of pneumonia and the risk of severe disease in patients with Delta infection of different ages. In the face of Delta, the full vaccination of domestic COVID-19 vaccines can reduce the risk of pneumonia in all ages by 50% to 70%, and reduce the risk of severe disease by 70% to 80%, while the two figures of enhanced vaccination are 86% and 91% to 98%, respectively.
In the face of Aumechon, full vaccination can reduce the risk of pneumonia in people over 60 years old, and enhanced vaccination can reduce the risk of severe illness. In unvaccinated people, Delta infection was more severe than Omilon infection.
Real-world data verify the effectiveness of domestic vaccines
The researchers pointed out that due to the implementation of the "dynamic clearance" policy in China, there are very few cases of new crown in the country, and almost all of the immunity of Chinese comes entirely from the vaccine, rather than the mixed immunity of infection and vaccine. As vaccination coverage increases and the spread of Delta and Omilkeron variants increases, so do the number of COVID-19 breakthrough cases. The degree to which vaccines maintain protection is key to assessing the strength of herd immunity and has important implications for the adjustment of immunization strategies.
It is worth noting that real-world studies from abroad have also shown that timely vaccination of domestic COVID-19 vaccines can effectively reduce the risk of infection, severe illness and death.
China's biological COVID-19 vaccine has been registered and listed in 119 countries, regions and international organizations around the world, covering 196 countries, with an annual production capacity of more than 10 billion doses, and a cumulative supply of 3.5 billion doses to global production.
On May 3, 2021, the World Health Organization released the evaluation report of the new crown inactivated vaccine of the Beijing Institute of Biological Products of China Biologics, which found that the protective efficacy of the vaccine was 78.1%, up to 90%, and the safety was good. Marianela Simão, WHO Assistant Director-General for Access to Medicines and Health Products, said that the inclusion of Sinopharm's Bio-COVID-19 vaccine in THE WHO's emergency use list "helps countries seeking to protect health workers and high-risk groups accelerate access to COVID-19 vaccines".
On June 30, 2021, the Argentine Ministry of Health released a report announcing the results of the real-world study of Sinopharm China Biological Vaccine in preventing the death of infected people over the age of 60 in the country's COVID-19 vaccination from January to June 2021. The results showed that the overall death protection rate of two doses of Chinese biological vaccine against people over 60 years old was 84%, of which 80.2% for 60-69 years old, 88.3% for 70-79 years old, and 77.6% for 80 years old and older.
It is very safe for children to be vaccinated. On November 18, 2021, Argentina's National Committee for Vaccine Safety released the Child and Adolescent Vaccine Safety Report, which included data from which 4728885 doses of COVID-19 vaccine were injected into children (3-11 years) and adolescents (12-17 years). Among them, Sinopharm China Biological Covid-19 vaccine has the largest dose, with 1932165 doses, while the adverse reaction event notification rate is the lowest, 7.9/100,000.
On April 20, at a press conference on the prevention and control of the new crown pneumonia epidemic in Shanghai, Sun Xiaodong, deputy director of the Shanghai Municipal Center for Disease Control and Prevention, introduced that as of now, the vaccination rate of the elderly aged 60 and over in Shanghai is 62%; the vaccination rate of strengthening is 38%. Overall, vaccination rates are low.
In this regard, Sun Xiaodong called on the eligible elderly to make an appointment for the new crown vaccine as soon as possible after the unsealing and opening of the nearby vaccination point in the future, and if the elderly who have completed the full vaccination, they should be vaccinated as soon as possible after 6 months.