Background To date, coronavirus disease 2019 (COVID-19) becomes increasingly fierce due to the emergence of variants. Rapid herd immunity through vaccination is needed to block the mutation and prevent the emergence of variants that can completely escape the immune surveillance. We aimed to systematically evaluate the effectiveness and safety of COVID-19 vaccines in the real world and to establish a reliable evidence-based basis for the actual protective effect of the COVID-19 vaccines, especially in the ensuing waves of infections dominated by variants. Methods We searched PubMed, Embase and Web of Science from inception to July 22, 2021. Observational studies that examined the effectiveness and safety of SARS-CoV-2 vaccines among people vaccinated were included. Random-effects or fixed-effects models were used to estimate the pooled vaccine effectiveness (VE) and incidence rate of adverse events after vaccination, and their 95% confidence intervals (CI). Results A total of 58 studies (32 studies for vaccine effectiveness and 26 studies for vaccine safety) were included. A single dose of vaccines was 41% (95% CI: 28–54%) effective at preventing SARS-CoV-2 infections, 52% (31–73%) for symptomatic COVID-19, 66% (50–81%) for hospitalization, 45% (42–49%) for Intensive Care Unit (ICU) admissions, and 53% (15–91%) for COVID-19-related death; and two doses were 85% (81–89%) effective at preventing SARS-CoV-2 infections, 97% (97–98%) for symptomatic COVID-19, 93% (89–96%) for hospitalization, 96% (93–98%) for ICU admissions, and 95% (92–98%) effective for COVID-19-related death, respectively. The pooled VE was 85% (80–91%) for the prevention of Alpha variant of SARS-CoV-2 infections, 75% (71–79%) for the Beta variant, 54% (35–74%) for the Gamma variant, and 74% (62–85%) for the Delta variant. The overall pooled incidence rate was 1.5% (1.4–1.6%) for adverse events, 0.4 (0.2–0.5) per 10 000 for severe adverse events, and 0.1 (0.1–0.2) per 10 000 for death after vaccination. Conclusions SARS-CoV-2 vaccines have reassuring safety and could effectively reduce the death, severe cases, symptomatic cases, and infections resulting from SARS-CoV-2 across the world. In the context of global pandemic and the continuous emergence of SARS-CoV-2 variants, accelerating vaccination and improving vaccination coverage is still the most important and urgent matter, and it is also the final means to end the pandemic. Graphical Abstract

COVID-19 infections are returning to many countries because of the emergence of variants or declining antibody levels provided by vaccines. An additional dose of vaccination is recommended to be a considerable supplementary intervention. We aim to explore public acceptance of the third dose of the COVID-19 vaccine and related influencing factors in China. This nationwide cross-sectional study was conducted in the general population among 31 provinces in November, 2021. We collected information on basic characteristics, vaccination knowledge and attitudes, and vaccine-related health beliefs of the participants. Univariable and multivariable logistic regression models were used to assess factors associated with the acceptance of a third COVID-19 vaccine. A total of 93.7% (95% CI: 92.9–94.6%) of 3119 Chinese residents were willing to receive a third dose of the COVID-19 vaccine. Individuals with low level of perceived susceptibility, perceived benefit, cues to action cues, and high level of perceived barriers, old age, low educational level, low monthly household income, and low knowledge score on COVID-19 were less likely to have the acceptance of a third dose of COVID-19 (all p < 0.05). In the multivariable logistic regression model, acceptance of the third dose of COVID-19 vaccine was mainly related to previous vaccination history [Sinopharm BBIP (aOR = 6.55, 95% CI 3.30–12.98), Sinovac (aOR = 5.22, 95% CI:2.72–10.02), Convidecia (aOR = 5.80, 95% CI: 2.04–16.48)], high level of perceived susceptibility (aOR = 2.48, 95% CI: 1.48–4.31) and high level of action cues (aOR = 23.66, 95% CI: 9.97–56.23). Overall, residents in China showed a high willingness to accept the third dose of COVID-19 vaccines, which can help vaccine manufacturers in China to manage the vaccine production and distribution for the huge domestic and international vaccine demand. Relevant institutions could increase people’s willingness to booster shots by increasing initial COVID-19 vaccination rates, public’s perception of COVID-19 susceptibility and cues to action through various strategies and channels. Meanwhile, it also has certain reference significance for other countries to formulate vaccine promotion strategies.

BackgroundMSM individuals are at high risk of monkeypox infection, and judicious use of vaccines can control the outbreak. Therefore, we conducted a national cross-sectional survey to assess the vaccination willingness, associated factors, and related knowledges of monkeypox among MSM individuals in China.MethodsThis anonymous cross-sectional study was conducted in China from July 1 to July 3, 2022, and electronic questionnaires were sent online to MSM individuals of specific institutions. Men, aged 18 or older, who had anal sex in the past year were recruited. Multivariable logistic regression models and univariable logistic regression models were performed in different groups of participants, including all eligible respondents, people with or without self-reported HIV infection, and people who had sex with at least one male sexual partner in last month.ResultsA total of 2,618 male respondents, including 2,134 homosexuals and 484 bisexuals, were enrolled in our final analysis. Most of the respondents had a certain understanding of the source of infection, transmission route, and preventive measures, but lacked knowledge of the susceptible population, clinical manifestations, vaccination, and treatment. In total, 90.2% of all respondents were willing to receive the vaccines against monkeypox. Among people with self-reported HIV infection, the vaccination acceptance rate was 91.7%, while it was 89.7% in the rest. The main influencing factors were knowledge about monkeypox (moderate: aOR = 1.47, 95% CI: 1.04–2.08; high: aOR = 2.03, 95% CI: 1.23–3.34), knowledge about prevention measures (moderate: aOR = 3.52, 95% CI: 2.51–4.94; high: aOR = 5.32, 95% CI: 2.98–9.47), concerns about their susceptibility to monkeypox infection (aOR = 4.37, 95% CI: 3.29–5.80), and possible contact with people and animals in epidemic areas (aOR = 0.42, 95% CI: 0.25–0.70). For self-reported HIV-infected individuals, education (bachelor degree: aOR = 0.40, 95% CI: 0.18–0.89) and poor condom use (sometimes: aOR = 2.18, 95% CI: 1.06–4.47) may also affect the vaccination.ConclusionsThere was still a lack of knowledge about the human monkeypox among MSM individuals in China. The vaccination acceptance rate of this high-risk population was high, and it was closely related to the knowledge factors, fear of infection, and possible contact with people or animals in affected areas. Targeted publicity and education of the high-risk groups, vaccination pre-arranged planning should be formulated to cope with the further development of this infectious disease.

Background: Given the prevalence of the omicron variant and decreased immunity provided by vaccines, it is imperative to enhance resistance to COVID-19 in the old population. We planned to explore the hesitancy rate toward the booster dose of the COVID-19 vaccine and the association between risk perception and the abovementioned rate among people aged 60 and older. Methods: This national cross-sectional study was conducted in mainland China from 25 May to 8 June 2022, targeting people who were 60 years old or above. Four dimensions were extracted from the Health Belief Model (HBM) to assess participants’ perceived risk levels, including perceived susceptibility, perceived severity, perceived barriers, and perceived benefit. An independent Chi-square test was used to compare the vaccine hesitancy rates among different groups stratified by characteristics. Univariable and multivariable logistic regression models were performed to explore the associations between risk perception and hesitancy rate. Results: Of 3321 participants, 17.2% (95% CI: 15.9–18.5%) were hesitant about booster shots of COVID-19 vaccines. Believing that they were ineligible for vaccination due to certain illnesses (38.3%), concern about vaccine safety (32.0%), believing the booster shots were unnecessary (33.1%), and their limitation on movements (28.0%) were the main reasons for vaccine hesitation. Adjusted by all the selected covariates, people with low perception level of susceptibility (aOR = 1.39, 95% CI: 1.00–1.92) and benefit (low: aOR = 3.31, 95% CI: 2.01–5.45; moderate: aOR = 2.23, 95% CI: 1.75–2.85) were less likely to receiving the booster dose, and the same results were found in people with higher perceived barriers (moderate: aOR = 2.67, 95% CI: 2.13–3.35; high: aOR = 2.04, 95% CI: 1.14–3.67). Our estimates were stable in all four models. Conclusions: In total, 17.2% of the people aged 60 years and older in China were hesitant about booster dose of COVID-19 vaccines, and it was closely associated with a lower level of perceived susceptibility and benefit, as well as a higher level of perceived barriers. Concerns about contraindications, vaccine safety, and limited movements were the main reasons for vaccine hesitancy. Targeted public health measure is a priority to improve the understanding of the elderly on their own susceptibility and vulnerability and clear the obstacles to vaccination.

COVID-19 vaccine booster shots are necessary to provide durable immunity and stronger protection against the emerging SARS-CoV-2 variants. As a major platform for access to information, social media plays an important role in disseminating health information. This study aimed to evaluate hesitancy toward COVID-19 vaccine booster shots in China, assess its association with social media use, and provide information to manage social media. We conducted a cross-sectional study across all 31 provinces in mainland China from November 12, 2021, to November 17, 2021. In total, 3,119 of 3,242 participants completed the questionnaire (response rate = 96.2%). COVID-19 vaccine booster shot hesitancy rate in China was 6.5% (95% CI: 5.6–7.3). Unemployment (adjusted odds ratio [aOR] 2.428, 95% CI: 1.590–3.670), low monthly income (aOR 2.854,95% CI: 1.561–5.281), low scores of knowledge (aOR 0.917, 95% CI: 0.869–0.968) and low level of cues to action (aOR 0.773, 95% CI: 0.689–0.869) were associated with vaccine hesitancy. Compared with public social media, lower vaccine hesitancy was associated with high perceived importance of social media (aOR 0.252, 95% CI: 0.146–0.445) and official social media use (aOR 0.671, 95% CI: 0.467–0.954), while higher vaccine hesitancy was associated with traditional media use (aOR 3.718, 95% CI: 1.282–10.273). More efforts are needed to regulate the content of social media and filtering out misinformation. The role of official social media in disseminating health information should be enhanced.