Possible transmission of COVID-19 epidemic by a dog as a passive mechanical carrier of SARS-CoV-2, Chongqing, China, 2022.

An outbreak of coronavirus disease 2019 (COVID-19) was reported in Yongchuan district of Chongqing, China in March 2022, while the source was unknown. We aimed to investigate the origin and transmission route of the virus in the outbreak. We conducted field investigations for all cases and collected their epidemiological and clinical data. We performed gene sequencing and phylogenetic analysis for the cases, and draw the epidemic curve and the case relationship chart to analyze interactions and possible transmission mode of the outbreak. A total of 11 cases of COVID-19, including 5 patients and 6 asymptomatic cases were laboratory-confirmed in the outbreak. The branch of the virus was Omicron BA.2 which was introduced into Yongchuan district by a traveler in early March. Patient F and asymptomatic case G had never contact with other positive-infected individuals, but close contact with their pet dog that sniffed the discarded cigarette butts and stepped on the sputum of patient B. Laboratory test results showed that the dog hair and kennel were positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the 10 isolates were highly homologous to an epidemic strain in a province of China. The investigation suggested that the contaminated dog by SARS-CoV-2 can act as a passive mechanical carrier of the virus and might transmit the virus to humans through close contact. Our findings suggest that during the COVID-19 pandemic, increasing hygiene measures and hand washing after close contact with pets is essential to minimize the risk of community spread of the virus.

An Outbreak of SARS-CoV-2 Omicron Subvariant BA.2.76 in an Outdoor Park - Chongqing Municipality, China, August 2022.

What is already known about this topic?: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron subvariant has a stronger transmission capacity and faster transmission speed than the previous strain. What is added by this report?: The first coronavirus disease 2019 (COVID-19) case infected with the SARS-CoV-2 Omicron subvariant BA.2.76 who caused local transmission was reported in Chongqing Municipality on August 16, 2022. For 35 minutes, the Patient Zero jogged along a lake at a local park without wearing a mask. Among the 2,836 people potentially exposed at the time, 39 tested positive. Overall, 38 out of 39 cases did not wear a mask on the morning of August 16. All 39 cases lacked any previous exposure to the variant before testing positive on their nucleic acid test. What are the implications for public health practice?: It is essential to maintain personal wellbeing by ensuring one maintains personal protection and follows regulated guidelines such as maintaining safe distances from others both indoors and outdoors.

Humoral responses after inactivated COVID-19 vaccination in individuals with and without prior SARS-CoV-2 infection: A prospective cohort study.

We evaluated and compared humoral immune responses after inactivated coronavirus disease 2019 (COVID-19) vaccination among naïve individuals, asymptomatically infected individuals, and recovered patients with varying severity. In this multicenter, prospective cohort study, blood samples from 666 participants were collected before and after 2 doses of inactivated COVID-19 vaccination. Among 392 severe acute respiratory syndrome coronavirus 2-naïve individuals, the seroconversion rate increased significantly from 51.8% (median antispike protein pan-immunoglobulins [S-Igs] titer: 0.8 U/ml) after the first dose to 96% (median S-Igs titer: 79.5 U/ml) after the second dose. Thirty-two percent of naïve individuals had detectable neutralizing antibodies (NAbs) against the original strain but all of them lost neutralizing activity against the Omicron variant. In 274 individuals with natural infection, humoral immunity was significantly improved after a single vaccine dose, with median S-Igs titers of 596.7, 1176, 1086.5, and 1828 U/ml for asymptomatic infections, mild cases, moderate cases, and severe/critical cases, respectively. NAb titers also improved significantly. However, the second dose did not substantially increase antibody levels. Although a booster dose is needed for those without infection, our findings indicate that recovered patients should receive only a single dose of the vaccine, regardless of the clinical severity, until there is sufficient evidence to confirm the benefits of a second dose.

Mortality burden from seasonal influenza in Chongqing, China, 2012-2018.

PURPOSE: To estimate influenza-associated excess mortality rates (EMRs) in Chongqing from 2012 to 2018. METHODS: We obtained weekly mortality data for all-cause and four underlying causes of death (circulatory and respiratory disease (CRD), pneumonia and influenza (P&I), chronic obstructive pulmonary disease (COPD) and ischemic heart disease (IDH)), and influenza surveillance data, from 2012 to 2018. A negative-binomial regression model was used to estimate influenza-associated EMRs in two age groups (<65 years and ≥65 years). RESULTS: It was estimated that an annual average of 10025 influenza-associated deaths occurred in Chongqing, corresponding to 5.2% of all deaths. The average EMR for all-cause death associated with influenza was 33.5 (95% confidence interval (CI): 31.5-35.6) per 100 000 persons, and in separate cause-specific models we attributed 24.7 (95% CI: 23.3-26.0), 0.8 (95% CI: 0.7-0.8), 8.5 (95% CI: 8.1-9.0) and 5.0 (95% CI: 4.7-5.3) per 100 000 persons EMRs to CRD, P&I, COPD and IDH, respectively. The estimated EMR for influenza B virus was 20.6 (95% CI: 20.3-21.0), which was significantly higher than the rates of 5.3 (95% CI: 4.5-6.1) and 7.5 (95% CI: 6.7-8.3) for A(H3N2) and A(H1N1) pdm09 virus, respectively. The estimated EMR was 152.3 (95% CI: 136.1-168.4) for people aged ≥65 years, which was significantly higher than the rate for those aged <65 years (6.8, 95% CI: 6.3-7.2). CONCLUSIONS: Influenza was associated with substantial EMRs in Chongqing, especially among elderly people. Influenza B virus caused a relatively higher excess mortality impact compared with A(H1N1)pdm09 and A(H3N2). It is advisable to optimize future seasonal influenza vaccine reimbursement policy in Chongqing to curb disease burden.