SARS-CoV-2 antibody response among COVID-19 patients is not affected by parasite co-infection (preprint)

Background: B-cell hypo-responsiveness has been associated with intestinal parasitic co-infection. The effect of parasite co-infection on antibody response to SARS-CoV-2 is unknown. Here, we aimed to determine antibody response to SARS-CoV-2 among COVID-19 patients co-infected with intestinal parasites and those without parasite co-infection. Methods: In this prospective cohort study, a total of 589 samples were serially collected from 72 RT-PCR-confirmed patients. Anti-SARS-CoV-2 nucleocapsid protein (NP) antibody titers were measured longitudinally during hospitalization. SARS-CoV-2 infection was confirmed by RT-PCR on samples obtained from nasopharyngeal swabs, while direct microscopic examination, modified Ritchie concentration, and Kato-Katz methods were used to identify parasites and ova from fresh stool samples. Data were analyzed using STATA version 14. Results: Of the 72 COVID-19 patients, 39 (54.2%) were co-infected with intestinal parasites while 33 (45.8%) had no parasitic co-infection. Overall, the median cut-off index (COI) for anti-NP antibody titer among COVID-19 patients co-infected with parasites was 6.91 (IQR: 0.55-40.7) compared to 7.51 (IQR: 0.21-59.21) in those without parasites (p=0.764). In addition, 174/261 [66.7% (95% CI: 60.68-72.16)] and 231/328 [70.4% (95% CI: 65.23-75.14)] specimens from COVID-19 patients with parasite co-infection and without parasites, respectively, had anti-SARS-CoV-2 antibody above the cut-off COI value (p=0.328). The positivity rate for anti-SARS-CoV-2 NP < 14 days after symptom onset was 66.3% (95% CI: 60.21-71.85) and 70.0% (95% CI: 64.72-74.74) for those not infected and co-infected with parasites, respectively (p=0.343). In addition, 31/72 (41.9%) of the patients who were negative at the time of enrollment were seroconverted. The trend in anti-NP antibodies among seroconverted individuals with and without parasites is also similar. Conclusions: Co-infection with parasitic infection has very little effect on the anti-SARS-CoV-2 antibody immune response. Further studies on the profile of neutralizing antibodies in parasite-endemic areas are warranted to ascertain vaccine efficacy.

Long-term respiratory mucosal immune memory to SARS-CoV-2 after infection and vaccination (preprint)

Respiratory mucosal immunity induced by vaccination is vital for protection from coronavirus infection in animal models. In humans, SARS-CoV-2 immunity has been studied extensively in blood. However, the capacity of peripheral vaccination to generate sustained humoral and cellular immunity in the lung mucosa, and how this is influenced by prior SARS-CoV-2 infection, is unknown. Bronchoalveolar lavage samples obtained from vaccinated donors with or without prior infection revealed enrichment of spike-specific antibodies, class-switched memory B cells and T cells in the lung mucosa compared to the periphery in the setting of hybrid immunity, whereas in the context of vaccination alone, local anti-viral immunity was limited to antibody responses. Spike-specific T cells persisted in the lung mucosa for up to 5 months post-vaccination and multi-specific T cell responses were detected at least up to 11 months post-infection. Thus, durable lung mucosal immunity against SARS-CoV-2 seen after hybrid exposure cannot be achieved by peripheral vaccination alone, supporting the need for vaccines targeting the airways.

Streptococcus pneumoniae colonisation associates with impaired adaptive immune responses against SARS-CoV-2 (preprint)

Although recent epidemiological data suggest that pneumococci may contribute to the risk of SARS-CoV-2 disease, secondary pneumococcal pneumonia has been reported as infrequent. This apparent contradiction may be explained by interactions of SARS-CoV-2 and pneumococcus in the upper airway, resulting in the escape of SARS-CoV-2 from protective host immune responses. Here, we investigated the relationship of these two respiratory pathogens in two distinct cohorts of a) healthcare workers with asymptomatic or mildly symptomatic SARS-CoV-2 infection identified by systematic screening and b) patients with moderate to severe disease who presented to hospital. We assessed the effect of co-infection on host antibody, cellular and inflammatory responses to the virus. In both cohorts, pneumococcal colonisation was associated with diminished anti-viral immune responses, which affected primarily mucosal IgA levels among individuals with mild or asymptomatic infection and cellular memory responses in infected patients. Our findings suggest that S. pneumoniae modulates host immunity to SARS-CoV-2 and raises the question if pneumococcal carriage also enables immune escape of other respiratory viruses through a similar mechanism and facilitates reinfection occurrence.