Immunogenicity of Pfizer-BioNTech COVID-19 mRNA Primary Vaccination Series in Recovered Individuals Depends on Symptoms at Initial Infection.

ImportancePublic health vaccination recommendations for COVID-19 primary series and boosters in previously infected individuals differ worldwide. As infection with SARS-CoV-2 is often asymptomatic, it remains to be determined if vaccine immunogenicity is comparable in all previously infected subjects. We present detailed immunological evidence to clarify the requirements for one-or two-dose primary vaccination series for naturally primed individuals. ObjectiveEvaluate the immune response to COVID-19 mRNA vaccines in healthcare workers (HCWs) who recovered from a SARS-CoV-2 infection. DesignMulticentric observational prospective cohort study of HCWs with a PCR-confirmed SARS-CoV-2 infection designed to evaluate the dynamics of T and B cells immune responses to primary infection and COVID-19 mRNA vaccination over 12 months. ParticipantsUnvaccinated HCWs with PCR-confirmed SARS-CoV-2 infection were selected based on the presence or absence of symptoms at infection and serostatus at enrollment. Age- and sex-matched adults not infected with SARS-CoV-2 prior to vaccination were included as naive controls. ExposureVaccination with Pfizer BioNTech BNT162b2 mRNA vaccine. Main Outcome(s) and Measure(s)Immunity score (zero to three), before and after vaccination, based on anti-RBD IgG ratio, serum capacity to neutralize live virus and IFN-{gamma} secretion capacity in response to SARS-CoV-2 peptide pools above the positivity threshold for each of the three assays. We compared the immunity score between groups based on subjects symptoms at diagnosis and/or serostatus prior to vaccination. ResultsNone of the naive participants (n=14) showed a maximal immunity score of three following one dose of vaccine compared to 84% of the previously infected participants (n=55). All recovered individuals who did not have an immunity score of three were seronegative prior to vaccination, and 67% had not reported symptoms resulting from their initial infection. Following one dose of vaccine, their immune responses were comparable to naive individuals, with significantly weaker responses than those who were symptomatic during infection. Conclusions and RelevanceIndividuals who did not develop symptoms during their initial SARS-CoV-2 infection and were seronegative prior to vaccination present immune responses comparable to that of naive individuals. These findings highlight the importance of administering the complete two-dose primary regimen and following boosters of mRNA vaccines to individuals who experienced asymptomatic SARS-CoV-2 infection. KEY POINTS QuestionIs a single dose of COVID-19 mRNA vaccine sufficient to induce robust immune responses in individuals with prior SARS-CoV-2 infection? FindingsIn this cohort of 55 health care workers previously infected with SARS-CoV-2, we show that the absence of symptoms during initial infection and negative serostatus prior to vaccination predict the strength of immune responses to COVID-19 mRNA vaccine. Lack of symptoms and a negative serostatus prior to vaccination leads to immune responses comparable to naive individuals. MeaningOur results support a two-dose primary series requirement for any individual with prior history of asymptomatic SARS-CoV-2 infection.

Adequacy of serial self-performed SARS-CoV-2 rapid antigen-detection testing for longitudinal mass screening in the workplace

ImportanceLongitudinal mass testing using rapid antigen detection tests (RADT) for serial screening of asymptomatic persons has been proposed for preventing SARS-CoV-2 community transmission. The feasibility of this strategy relies on implementation of accurate self-performed RADT testing where people live, work, or attend school. ObjectiveTo quantify the adequacy of serial self-performed SARS-CoV-2 RADT testing in the workplace, in terms of the frequency of correct execution of procedural steps and accurate interpretation of the range of possible RADT results. We compared results using the instructions provided by the manufacturer to those with modified instructions that were informed by the most frequent or most critical errors we observed. DesignRepeated cross-sectional, diagnostic accuracy study performed prospectively in the field. SettingBusinesses in Montreal, Quebec, Canada, with at least 2 active cases of SARS-CoV-2 infection. ParticipantsUntrained, asymptomatic persons in their workplace, not meeting Public Health quarantine criteria. ExposuresA Modified Quick Reference Guide compared to the original manufacturers instructions. Main Outcome(s) and Measure(s)The difference in the proportions of correctly performed procedural steps, and the difference in proportions of correctly interpreted RADT proficiency panel results. The secondary outcome, among subjects with two self-testing visits, compared the second to the first self-test visit using the same measures. ResultsOverall, 1892 tests were performed among 647 subjects. For self-test visit 1, significantly better accuracy in test interpretation was observed using the Modified Quick Reference Guide for weak positive (55.6% vs. 12.3%; 43.3 percentage point improvement, 95% confidence interval [CI] 33.0%-53.8%), positive (89.6% vs. 51.5%; 38.1% difference, 95%CI 28.5%-47.5%), strong positive (95.6% vs. 84.0%; 11.6% improvement, 95%CI 6.8%-16.3%) and invalid (87.3% vs. 77.3%; 10.0% improvement, 95%CI 3.8%-16.3%) tests. Use of the modified guide was associated with smaller, statistically significant, improvements on self-test visit 2. For procedural steps identified as critical for the validity of test results, adherence to procedural testing steps did not differ meaningfully according to instructions provided or reader experience. Conclusions and RelevanceLongitudinal mass RADT testing for SARS-CoV-2 can be accurately self-performed in an intended-use setting; this work provides evidence for how to optimise performance. Key PointsO_ST_ABSQuestioC_ST_ABSDo untrained users correctly perform and interpret the results of SARS-CoV-2 rapid antigen detection tests (RADT) in the workplace, and how can their performance be optimised? FindingsIn this prospective field evaluation of self-performed SARS-CoV-2 RADT in an intended-use setting, we found that the accuracy of RADT interpretation was poor when the manufacturers instructions were used. A Modified Quick Reference Guide yielded significantly better user performance. MeaningLongitudinal mass RADT testing for SARS-CoV-2 can be accurately self-performed in an intended-use setting; this work provides evidence for how to optimise performance.

Durability and Cross-Reactivity of Immune Responses Induced by an AS03 Adjuvanted Plant-Based Recombinant Virus-Like Particle Vaccine for COVID-19

As the SARS-COV-2 pandemic evolves, what is expected of vaccines extends beyond efficacy to include consideration of both durability and variant cross-reactivity. This report expands on previously reported immunogenicity results from a Phase 1 trial of an AS03-adjuvanted, plant-based coronavirus-like particle (CoVLP) displaying the spike (S) glycoprotein of the ancestral SARS-CoV-2 virus in healthy adults 18-49 years of age (NCT04450004). When humoral and cellular responses against the ancestral strain were evaluated 6 months post-second dose (D201), 100% of vaccinated individuals retained binding antibodies, and [~]95% retained neutralizing antibodies; interferon gamma (IFN-{gamma}) and interleukin 4 (IL-4) responses directed against the ancestral S protein were also still detectable in [~]94% and [~]92% of vaccinees respectively. Variant-specific, cross-reactive neutralizing antibody (NAb) levels were assessed at D42 and D201 using both live wild-type and pseudovirion assays (Alpha, Beta, Gamma) or the wild-type assay alone (Delta, Omicron). In the wild-type assay, broad cross-reactivity was detected against all variants at D42 (100% Alpha and Delta, 94% Beta and Gamma, 74% Omicron). At D201, cross-reactive antibodies were detectable in almost all participants against Alpha, Gamma and Delta variants (94%) and the Beta variant (83%) and in a smaller proportion against Omicron (44%). Results were similar in the pseudovirion assay (D42, 100% cross-reactivity to Alpha and Gamma variants, 95% to Beta variant, D201, 94% for Alpha, Beta and Gamma variants). These data suggest that two doses of 3.75 {micro}g CoVLP+AS03 elicit a durable and cross-reactive response that persists for at least 6 months post-vaccination.

Inpatient outcomes for hospitalized older adults with rhinovirus.

BackgroundRhinoviruses account for many cases of the "common cold" and infection is often self-limiting. As such, there is a lack of data regarding the inpatient outcomes of individuals hospitalized with rhinovirus infection. Given the generalized poorer prognosis of elderly admitted with respiratory viral infections, we assessed the mortality rate of general medical patients admitted with rhinovirus infection along with the major risk factors associated to mortality. MethodsWe performed a retrospective chart review of patients admitted to our clinical teaching ward from December 2013 to June 2017. ResultsOverall, 12.5% of patients admitted with rhinovirus infection died within 90 days of admission. The median age of admitted patients was 70 years-old. In univariable analysis, age (OR 1.05; 95% confidence interval (CI) 1.01-1.09) and the need for oxygen at presentation (OR 3.23; 95% CI 1.06-9.86) were associated with death while obstructive pulmonary disease or asthma (OR 0.10; 95% CI 0.01-0.81) was associated with survival. In the multivariable model, age (aOR 1.04; 95% CI 1.00-1.09) and obstructive lung disease (aOR 0.09 95%CI 0.01-0.73) remained significant whereas the requirement for oxygen at presentation did not (aOR 2.78; 95% CI 0.84-9.23). ConclusionOur study reveals that rhinovirus is an important cause of both morbidity and mortality in the elderly and further highlights the need for studies of potentially effective treatment options. In the meantime, we suggest that rigorous respiratory hygiene measures and quality older adult care should be practiced when caring for at-risk adults.

Phase 1 trial of a Candidate Recombinant Virus-Like Particle Vaccine for Covid-19 Disease Produced in Plants

Longer AbstractO_ST_ABSBackgroundC_ST_ABSThe stabilized prefusion form of the SARS-CoV-2 spike protein is produced by transient expression in Nicotiana benthamiana. The trimeric spike glycoproteins are displayed at the surface of self-assembling Virus-Like-Particles that mimic the shape and the size of the virus. The candidate vaccine (CoVLP) administered alone or with AS03 or CpG1018 adjuvants was evaluated in a Phase 1 trial in healthy adults. (ClinicalTrials.gov number NCT04450004) MethodsThe study was a randomized, partially-blinded, prime-boost 21 days apart, dose-escalation Phase 1 study intended to assess the safety, tolerability, and immunogenicity of CoVLP at three dose levels (3.75 {micro}g, 7.5 {micro}g, and 15 {micro}g) unadjuvanted or adjuvanted with either CpG 1018 or AS03 in 180 SARS-CoV-2 seronegative healthy adults 18 to 55 years of age. Enrollment was staggered for dose-escalation. At each dose level, the vaccine was initially administered to a small number of subjects. Vaccination of the remaining subjects at the same dose level and the next higher vaccine dose level was administered with approval of an Independent Data Monitoring Committee (IDMC). The same procedure was followed for the second vaccine administration. Monitoring of safety signals was performed throughout the study with pre-determined pausing/stopping rules if there was clear evidence of harmful effects such as severe adverse events (AEs) related to the treatment. The primary endpoints were the safety and tolerability of the vaccine after each dose and the immunogenicity as assessed by neutralizing antibody responses assessed using a vesicular stomatitis virus (VSV) pseudovirion assay and interferon-gamma (IFN-{gamma}) and interleukin-4 (IL-4) ELISpot assays at Days 0, 21 and 42. Secondary endpoints were anti-spike antibody responses by ELISA and neutralizing antibodies measured by live virus plaque reduction neutralization test (PRNT) assay at Days 0, 21 and 42 and immunogenicity with additional safety and immunogenicity endpoints planned for 6-months following the last vaccination. The anti-spike and neutralizing antibody responses were compared with 23 convalescent serum samples from symptomatic Covid-19 patients. We performed a primary analysis at day 42. ResultsA total of 180 subjects (102 females: 78 males: average 34.3 years) were recruited to the study and interim safety and immunogenicity data up to day 42 after the first dose are reported here. There was no obvious CoVLP dose effect in safety outcomes for any of the formulations tested and all formulations were generally well-tolerated. Most solicited local and systemic AEs were mild-moderate and transient. Reactogenicity was increased in all adjuvanted formulations and was generally highest in the CoVLP+AS03 groups. Local and systemic adverse events were reported with similar frequency after the first and second doses in subjects who received either CoVLP alone or CoVLP+CpG1018 but increased in both frequency and severity after the second dose in the CoVLP+AS03 groups. CoVLP alone only elicited a weak total anti-spike IgG response at the highest dose level and little-to-no neutralization antibody response, even after the second dose. Cellular responses in the CoVLP alone groups (IFN{gamma} and IL-4) were detectable after the second dose but were still only marginally above background levels. The addition of either adjuvant substantially increased both antibody and cellular responses at most CoVLP dose levels and changes were most pronounced after the second dose. However, a substantial neutralizing antibody response after the first dose was only seen in all CoVLP+AS03 groups. After the second dose, both total anti-spike IgG and neutralizing antibody titers in the CoVLP+AS03 groups were higher than those in the CoVLP+CpG1018 groups. The antibody titers achieved were either similar to (CoVLP+CpG1018) or at least 10-times higher (CoVLP+AS03) than those seen in convalescent plasma. Administration of CoVLP with either adjuvant also significantly increased the cellular responses. After 2 doses, both IFN-{gamma} and IL-4 responses were significantly increased in the CoVLP+CpG1018 groups. In the CoVLP+AS03 groups, significant increases in the cellular responses were observed after the first dose while IFN-{gamma} and IL-4 increased further in both magnitude and number of subjects responding after the second dose. Again, the cellular responses in the CoVLP+AS03 groups were higher than those seen in the CoVLP+CpG1018 groups. ConclusionThese data demonstrate that CoVLP administered with either CpG1018 or AS03 has a safety profile similar to other candidate vaccines for SARS-CoV-2. When administered with either AS03 or CpG1018, several of the CoVLP dose levels elicited strong humoral and T cell responses after the second dose. When administered with AS03, even the 3.75 g CoVLP dose elicited neutralizing antibody titers that were [~]10-times higher than those observed in individuals recovering from Covid-19 as well as consistent and balanced IFN-{gamma} and IL-4 responses. Although many CoVLP formulations were immunogenic, in the absence of established correlates of protection and given the advantages of dose-sparing in the context of the on-going pandemic, these findings suggest that CoVLP (3.75 g)+AS03 has a good benefit/risk ratio and support the transition of this formulation to studies in expanded populations and to efficacy evaluations Shorter AbstractO_ST_ABSBackgroundC_ST_ABSVirus-like particles (VLP) displaying recombinant SARS-CoV-2 spike protein trimers were produced by transient expression in Nicotiana benthamiana. This candidate vaccine (CoVLP) was evaluated in healthy adults 18-55 years of age alone or with AS03 or CpG1018 (NCT04450004). MethodsThis randomized, partially-blinded, two-dose, dose-escalation study assessed CoVLP (3.75, 7.5 or 15 {micro}g/dose) administered intramuscularly alone or with CpG1018 or AS03 in SARS-CoV-2 seronegative adults (18-55 years). Primary endpoints of safety and immunogenicity are reported to day 42. Neutralizing antibodies (NtAb) were assessed using a VSV pseudovirus assay and cellular responses by ELISpot (IFN{gamma}, IL-4). Results180 subjects (avg.34.3yrs) were recruited. All formulations were well-tolerated but adjuvants increased reactogenicity. Adverse events were highest in the CoVLP+AS03 groups and increased in frequency/severity after dose two. CoVLP alone elicited weak humoral responses but modest cellular responses were detectable after dose two. Both adjuvants increased immunogenicity significantly, particularly after dose two. A significant NtAb response after dose one was only seen in CoVLP+AS03 groups. The vaccine dose had little impact on levels of NtAb responses achieved in the CoVLP+AS03 groups. Both adjuvants also increased IFN{gamma} and IL-4 responses but these cellular responses also tended to be highest in the AS03-adjuvanted groups. ConclusionCoVLP {+/-} adjuvants was well-tolerated. Several adjuvanted formulations elicited strong humoral and T cell responses after dose 2. Even at the lowest CoVLP+AS03 dose, NtAb titers were [~]10-times higher than in convalescent serum with a balanced IFN{gamma} and IL-4 response. These findings support the transition of CoVLP (3.75g+AS03) to further clinical evaluation. Research In ContextO_ST_ABSEvidence before this studyC_ST_ABSThe severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was recognized as the causative agent of COVID-19 in early 2020. Since that time, >150 candidate vaccines are reported to be under development of which 47 have entered clinical trials (https://www.who.int/publications/m/item/draft-landscape-of-covid-19-candidate-vaccines accessed Nov 4, 2020). No vaccine to prevent COVID-19 has been licensed yet for either emergency or general use in North America or Europe. We searched PubMed for research articles published between July 2019 and November 4, 2020, using the terms "SARS-CoV-2", "vaccine", "clinical trial" OR "human", AND "phase". The same terms were used to search ClinTrials.gov. No language restrictions were applied. We identified 10 peer-reviewed studies, describing phase 1 or 1/2 trials using a range of novel (eg: RNA, DNA, non-replicating virus vectored) and more traditional vaccine approaches (eg: inactivated virus or recombinant protein {+/-} adjuvants). None of these candidate vaccines was produced in plants. These reports demonstrate that several different vaccination strategies (typically delivered in two doses 14-28 days apart) are capable of eliciting neutralizing antibody responses. In several cases, vaccine-induced cellular responses against SARS-COV-2 antigens - predominantly the spike (S) protein - can also be demonstrated. Although local and systemic adverse events following vaccination have varied between reports, the trials published to date suggest that each of these candidate vaccines is well-tolerated in the context of an evolving pandemic. Added value of this studyWe report the results of the first clinical study of CoVLP, a virus-like particle (VLP) vaccine that is produced by transient transfection of Nicotiana benthamiana plants. These VLPs spontaneously assemble at the plant cell membrane and display SARS-COV-2 trimers of stabilized pre-fusion S protein on their surface. The vaccine was administered as two intramuscular doses 21 days apart at three dose levels (S protein content 3.75, 7,5 or 15g) alone or adjuvanted with either CpG1018 or AS03. All formulations were well-tolerated although both adjuvants increased reactogenicity. Humoral (anti-S IgG and neutralizing antibodies) as well as cellular responses (IFNg and IL4 ELISpots) were detectable in almost all subjects who received adjuvanted formulations 21 days after the second dose at all COVLP dose levels. Both antibody and cellular responses were highest in subjects who received AS03-adjuvanted formulations. Even at the lowest dose level (3.75g), the neutralizing antibody titers 21 days after the second dose in subjects who received the AS03-afdjuvanted vaccine were 10-50-fold higher than those seen in subjects recovering from COVID-19 infection. Implications of all the available evidenceEffective vaccines against SARS-CoV-2 are urgently needed to reduce the burden of disease and contribute to ending the global pandemic. Although no immune correlates for SARS-CoV-2 have been defined, it is likely that both arms of the immune system contribute to protection. After two doses of CoVLP (3.75g+AS03), strong humoral and cellular responses were induced supporting the further clinical development of this vaccine.