Antibody response durability following three-dose COVID-19 vaccination in people with HIV receiving suppressive ART

BackgroundLimited data exist regarding longer-term antibody responses following three-dose COVID-19 vaccination, and the impact of a first SARS-CoV-2 infection during this time, in people living with HIV (PLWH) receiving suppressive antiretroviral therapy (ART). We quantified wild-type-(WT), Omicron BA.1- and Omicron BA.5-specific responses up to six months post-third dose in 64 PLWH and 117 controls who remained COVID-19-naive or experienced their first SARS-CoV-2 infection during this time. DesignLongitudinal observational cohort. MethodsWe quantified WT- and Omicron-specific Anti-Spike receptor-binding domain IgG concentrations, ACE2 displacement activities and live virus neutralization at one, three and six months post-third vaccine dose. ResultsThird doses boosted all antibody measures above two-dose levels, but BA.1-specific responses remained significantly lower than WT-specific ones, with BA.5-specific responses lower still. Serum IgG concentrations declined at similar rates in COVID-19-naive PLWH and controls post-third dose (median WT- and BA.1-specific half-lives were between 66-74 days for both groups). Antibody function also declined significantly yet comparably between groups: six months post-third dose, BA.1-specific neutralization was undetectable in >80% of COVID-19 naive PLWH and >90% of controls. Breakthrough SARS-CoV-2 infection boosted antibody concentrations and function significantly above vaccine-induced levels in both PLWH and controls, though BA.5-specific neutralization remained significantly poorer than BA.1 even post-breakthrough. ConclusionsFollowing three-dose COVID-19 vaccination, antibody response durability in PLWH receiving ART is comparable to controls. PLWH also mounted strong responses to breakthrough infection. Due to temporal response declines however, COVID-19-naive individuals, regardless of HIV status, would benefit from a fourth dose within 6 months of their third.

Serial infection with SARS-CoV-2 Omicron BA.1 and BA.2 following three-dose COVID-19 vaccination

SARS-CoV-2 Omicron infections are common among individuals who are vaccinated or have recovered from prior variant infection, but few reports have documented serial Omicron infections. We characterized SARS-CoV-2 humoral responses in a healthy young person who acquired laboratory-confirmed Omicron BA.1.15 ten weeks after a third dose of BNT162b2, and BA.2 thirteen weeks later. Responses were compared to those of 124 COVID-19 naive vaccinees. One month after the second and third vaccine doses, the participants wild-type and BA.1-specific IgG, ACE2 competition and virus neutralization activities were average for a COVID-19 naive triple-vaccinated individual. BA.1 infection boosted the participants responses to the cohort [≥]95th percentile, but even this strong "hybrid" immunity failed to protect against BA.2. Moreover, reinfection increased BA.1 and BA.2-specific responses only modestly. Results illustrate the risk of Omicron infection in fully vaccinated individuals and highlight the importance of personal and public health measures as vaccine-induced immune responses wane.

People with HIV receiving suppressive antiretroviral therapy show typical antibody durability after dual COVID-19 vaccination, and strong third dose responses

BackgroundLonger-term humoral responses to two-dose COVID-19 vaccines remain incompletely characterized in people living with HIV (PLWH), as do initial responses to a third dose. MethodsWe measured antibodies against the SARS-CoV-2 spike protein receptor-binding domain, ACE2 displacement and viral neutralization against wild-type and Omicron strains up to six months following two-dose vaccination, and one month following the third dose, in 99 PLWH receiving suppressive antiretroviral therapy, and 152 controls. ResultsThough humoral responses naturally decline following two-dose vaccination, we found no evidence of lower antibody concentrations nor faster rates of antibody decline in PLWH compared to controls after accounting for sociodemographic, health and vaccine-related factors. We also found no evidence of poorer viral neutralization in PLWH after two doses, nor evidence that a low nadir CD4+ T-cell count compromised responses. Post-third-dose humoral responses substantially exceeded post-second-dose levels, though anti-Omicron responses were consistently weaker than against wild-type. Nevertheless, post-third-dose responses in PLWH were comparable to or higher than controls. An mRNA-1273 third dose was the strongest consistent correlate of higher post-third-dose responses. ConclusionPLWH receiving suppressive antiretroviral therapy mount strong antibody responses after two- and three-dose COVID-19 vaccination. Results underscore the immune benefits of third doses in light of Omicron.

Rapid detection of SARS-CoV-2 variants of concern identifying a cluster of B.1.1.28/P.1 variant in British Columbia, Canada

Using a real-time RT-PCR-based algorithm to detect SARS-CoV-2 variants of concern, we rapidly identified 77 variants (57-B.1.1.7, 7-B.1.351, and 13-B.1.1.28/P.1). This protocol enabled our laboratory to screen all SARS-CoV-2 positive samples for variants, and identified a cluster of B.1.1.28/P.1 cases, a variant not previously known to circulate in British Columbia.

Diagnostic accuracy of RT-PCR for detection of SARS-CoV-2 compared to a composite reference standard in hospitalized patients

BackgroundCOVID-19 caused by the novel coronavirus SARS-CoV-2 has caused the greatest public health emergency of our time. Accurate laboratory detection of the virus is critical in order to contain the spread. Although real-time polymerase chain reaction (PCR) has been the cornerstone of laboratory diagnosis, there have been conflicting reports on the diagnostic accuracy of this method. MethodsA retrospective review was performed on all hospitalized patients tested for SARS-CoV-2 (at St. Pauls Hospital in Vancouver, BC) from March 13 - April 12, 2020. Diagnostic accuracy of initial PCR on nasopharyngeal (NP) swabs was determined against a composite reference standard which included a clinical assessment of the likelihood of COVID-19 by medical experts, initial and repeat PCR, and post-hoc serological testing. ResultsA total of 323 patients were included in the study, 33 (10.2%) tested positive and 290 (89.8%) tested negative by initial PCR. Patients testing positive were more likely to exhibit features of cough (66.7% vs 39.3%), shortness of breath (63.6% vs 35.9%), fever (72.7% vs 27.6%), radiographic findings (83.3% vs 39.6%) and severe outcomes including ICU admission (24.2% vs 9.7%) and mortality (21.2% vs 6.2%) compared to patients testing negative. Serology was performed on 90 patients and correlation between serology and PCR was 98.9%. There were 90 patients included in the composite reference standard. Compared to the composite reference standard, initial PCR had sensitivity of 94.7% (95% CI 74.0 to 99.9%), specificity of 100% (95% CI 94.9 to 100%), positive predictive value of 100% (95% CI 81.5 to 100%) and a negative predictive value of 98.6% (95% CI 92.5 to 100%). DiscussionOur study showed high sensitivity of PCR on NP swab specimens when compared to composite reference standard in hospitalized patients. High correlation of PCR with serological testing further increased confidence in the diagnostic reliability of properly collected NP swabs.

Practical challenges to the clinical implementation of saliva for SARS-CoV-2 detection

Due to global shortages of flocked nasopharyngeal swabs and appropriate viral transport media during the COVID-19 pandemic, alternate diagnostic specimens for SARS-CoV-2 detection are sought. The accuracy and feasibility of saliva samples collected and transported without specialized collection devices or media were evaluated. Saliva demonstrated good concordance with paired nasopharyngeal swabs for SARS-CoV-2 detection in 67/74 cases (90.5%), though barriers to saliva collection were observed in long-term care residents and outbreak settings. SARS-CoV-2 RNA was stable in human saliva at room temperature for up to 48 hours after initial specimen collection, informing appropriate transport time and conditions.

Evaluation of nasopharyngeal swab collection techniques for nucleic acid recovery and participant experience: recommendations for COVID-19 diagnostics

Nasopharyngeal swabs are critical to the diagnosis of respiratory infections including COVID-19, but collection techniques vary. We compared two recommended nasopharyngeal swab collection techniques in adult volunteers and found that swab rotation following nasopharyngeal contact did not recover additional nucleic acid (as measured by human DNA/RNA copy number). Rotation was also less tolerable for participants. Notably, both discomfort and nucleic acid recovery were significantly higher in Asians, consistent with nasal anatomy differences. Our results suggest that it is unnecessary to rotate the swab in place following contact with the nasopharynx, and reveal that procedural discomfort levels can differ by ethnicity. summaryNasopharyngeal swabs are critical to COVID-19 diagnostics, but collection techniques vary. Comparison of two collection techniques revealed that swab rotation did not recover more nucleic acid and was more uncomfortable. Discomfort and biological material recovery also varied by participant ethnicity.

Automated molecular testing of saliva for SARS-CoV-2 detection

With surging global demand for increased SARS-CoV-2 testing capacity, clinical laboratories seek automated, high-throughput molecular solutions, particularly for specimen types which do not rely upon supply of specialized collection devices or viral transport media (VTM). Saliva was evaluated as a diagnostic specimen for SARS-CoV-2 using the cobas(R) SARS-CoV-2 Test on the cobas(R) 6800 instrument. Saliva specimens submitted from various patient populations under investigation for COVID-19 from March-July 2020 were processed in the laboratory with sterile phosphate-buffered saline in a 1:2 dilution and vortexed with glass beads. The processed saliva samples were tested using a commercial assay for detection of the SARS-CoV-2 E gene (LightMix(R)) in comparison to the cobas(R) SARS-CoV-2 Test. 22/64 (34.4%) of the saliva samples were positive for SARS-CoV-2. Positive and negative concordance between the LightMix(R) and cobas(R) assays were 100%. There was no cross-contamination of samples observed on the cobas(R) 6800. The overall invalid rate for saliva on the cobas(R) 6800 (1/128, 0.78%) was similar to the baseline invalid rate observed for nasopharyngeal swabs/VTM and plasma samples. Saliva is a feasible specimen type for SARS-CoV-2 testing on the cobas(R) 6800, with potential to improve turnaround time and enhance testing capacity.

Suboptimal biological sampling as a probable cause of false-negative COVID-19 diagnostic test results

Improper nasopharyngeal swab collection could contribute to false-negative COVID-19 results. In support of this, specimens from confirmed or suspected COVID-19 cases that tested negative or indeterminate (i.e. suspected false-negatives) contained less human DNA (a stable molecular marker of sampling quality) compared to a representative pool of specimens submitted for testing.