ABSTRACT
Rhinovirus (RV) is one of the pathogens causing acute and chronic respiratory illnesses worldwide in paediatric patients. Compulsory mask-wearing and high stringency of social distancing were executed in Hong Kong since the SARSCoV-2 outbreak. While other common respiratory viruses vanished in routine surveillance programme, two sudden upsurges of RV associated upper respiratory tract infections were observed from Oct. to Nov. 2020 after schools reopening, and Apr. to Aug. 2021. We aimed to investigate if these RVs have a prominent role in transmission by analysing the RV genotype composition, assessing their replication competence, and the clinical features of paediatric patients. RV specimens collected from the hospitalised patients were genotyped, with clinical features of the patient documented and compared to those obtained in the pre-COVID-19 period. The replication competence of the RVs was examined in the well-differentiated human nasopharyngeal epithelial cells (HNPEC), and the stability of the RVs on different materials was tested. We identified the monopoly of minor group RV in each of the study duration, namely RV-A47 (80%) and RV-A49 (51%), respectively. In contrast to a diversified RV genotype composition in 2018-19. Without prior in vitro adaptation, the two minor-group RVs replicated in the HNPECs effectively to a comparable level as in the laboratory strain RVA16. The rise of minor-group RVs and dominance of single RV genotype under strict social distancing and hand hygiene is remarkable. Further investigation of the viral determinant, with an assessment of transmissibility in an animal model, will be needed to validate the specific role of these RVs.
ABSTRACT
Vaccines that elicit mucosal immune responses against SARS-CoV-2 could potent ially be of exceptional importance in providing first line defence at the site of viral entry. In order to understand the mucosal immune response profiles of SARS-CoV-2 vaccines, we examined both the mucosal and systemic responses of subjects vaccinated by two different vaccination platforms: mRNA (Comirnaty) and inactivated virus (CoronaVac). Nasal epithelial lining fluid (NELF) and peripheral blood samples were collected in subjects who had received two doses of CoronaVac or Comirnaty. We quantified IgA and IgG specific to SARS-CoV-2 S1 protein, neutralisation antibody by ELISA in NELF and plasma samples. Only Comirnaty induced nasal S1-specific IgA and IgG responses, which were evident as early as on 14±2 days after the first dose. The NELF samples of 72% of subjects became IgA+IgG+, while in 62.5% of subjects the samples were neutralising by 7±2 days after the second dose. In 45% of the subjects their NELF remained neutralising 50 days after the booster. In plasma, 91% and 100% Comirnaty subjects possessed S1-specific IgA+IgG+ on 14±2 days after the first dose and 7±2 days after booster, respectively. The plasma collected on 7±2 days after booster was 100% neutralising. The induction of S1-specific antibody by CoronaVac was IgG dominant, and 70% of the subjects possessed specific IgG by 7±2 days after booster and were all neutralising. This study reveals that Comirnaty is able to induce S1-specific IgA and IgG r esponse with neutralising activity in the nasal mucosa in addition to a consistent systemic response.