Hidden fraction of Polish population immune to SARS-CoV-2 in May 2021.

Population immunity (herd immunity) to SARS-CoV-2 derives from two sources: vaccinations or cases of infection with the virus. Infections can be diagnosed as COVID-19 and registered, or they can be asymptomatic, oligosymptomatic, or even full-blown but undiagnosed and unregistered when patients recovered at home. Estimation of population immunity to SARS-CoV-2 is difficult and remains a subject of speculations. Here we present a population screening for SARS-CoV-2 specific IgG and IgA antibodies in Polish citizens (N = 501) who had never been positively diagnosed with or vaccinated against SARS-CoV-2. Serum samples were collected in Wroclaw (Lower Silesia) on 15th and 22nd May 2021. Sera from hospitalized COVID-19 patients (N = 22) or from vaccinated citizens (N = 14) served as positive controls. Sera were tested with Microblot-Array COVID-19 IgG and IgA (quantitative) that contain specific SARS-CoV-2 antigens: NCP, RBD, Spike S2, E, ACE2, PLPro protein, and antigens for exclusion cross-reactivity with other coronaviruses: MERS-CoV, SARS-CoV, HCoV 229E Np, HCoV NL63 Np. Within the investigated population of healthy individuals who had never been positively diagnosed with or vaccinated against SARS-CoV-2, we found that 35.5% (178 out of 501) were positive for SARS-CoV-2-specific IgG and 52.3% (262 out of 501) were positive for SARS-CoV-2-specific IgA; 21.2% of the investigated population developed virus-specific IgG or IgA while being asymptomatic. Anti-RBD IgG, which represents virus-neutralizing potential, was found in 25.6% of individuals (128 out of 501). These patients, though positive for anti-SARS-CoV-2 antibodies, cannot be identified in the public health system as convalescents due to undiagnosed infections, and they are considered unaffected by SARS-CoV-2. Their contribution to population immunity against COVID-19 should however be considered in predictions and modeling of the COVID-19 pandemic. Of note, the majority of the investigated population still lacked anti-RBD IgG protection (74.4%); thus vaccination against COVID-19 is still of the most importance for controlling the pandemic.

SARS-CoV-2 IgG Amongst Dental Workers During the COVID-19 Pandemic.

OBJECTIVES: Since the SARS-CoV-2 outbreak in 2019, special safety protocols have been introduced in dentistry. Dental professionals were determined to be mostly at risk for contracting the virus due to aerosol-generating procedures used. This preliminary study starts the cycle of the laboratory protocols describing the quality and efficacy of laboratory tests in the SARS-CoV-2 immunoglobulin G (IgG) detection in the serum of asymptomatic dental personnel during the last quarter of 2020. METHODS: IgG levels were measured with the use of a semi-quantitative enzyme-linked immunosorbent assay (ELISA) in vitro diagnostic kit in the serum of a study group that consisted of 127 employees of the dental clinic divided into 3 subgroups: SUB1: dentists (n = 67); SUB2: dental assistants, dental hygienists, nurses, laboratory workers (n = 40); SUB3: administrative workers (n = 20). Pearson analysis of results from the questionnaires attached to the study protocol were provided to assure that the results compare to the participants' impressions about their general health. RESULTS: Positive ELISA IgG results were found in 6% (n = 4) of the SUB1 group, 7.50% (n =3) of the SUB2 group, and 5% of the SUB3 group. The percentage of participants without work interruption from the beginning of the pandemic was 54% of dentists and 60% of chairside assistants. CONCLUSIONS: Serum IgG prevalence with the use of a semi-quantitative test was low, and further research on the biobanked samples should follow to determine the levels of IgG with quantitative methods and/or to evaluate the presence of neutralising antibodies in dental personnel. Because of the low representation of seropositivity studies in this group, it will be crucial to confirm the risk of COVID-19 transmission in dental offices.

Antibodies specific to SARS-CoV-2 proteins N, S and E in COVID-19 patients in the normal population and in historical samples.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally; recognition of immune responses to this virus will be crucial for coronavirus disease 2019 (COVID-19) control, prevention and treatment. We comprehensively analysed IgG and IgA antibody responses to the SARS-CoV-2 nucleocapsid protein (N), spike protein domain 1 (S1) and envelope protein (E) in: SARS-CoV-2-infected patient, healthy, historical and pre-epidemic samples, including patients' medical, epidemiological and diagnostic data, virus-neutralizing capability and kinetics. N-specific IgG and IgA are the most reliable diagnostic targets for infection. Serum IgG levels correlate to IgA levels. Half a year after infection, anti-N and anti-S1 IgG decreased, but sera preserved virus-inhibitory potency; thus, testing for IgG may underestimate the protective potential of antibodies. Historical and pre-epidemic sera did not inhibit SARS-CoV-2, thus its circulation before the pandemic and a protective role from antibodies pre-induced by other coronaviruses cannot be confirmed by this study.

Role of Laboratory Medicine in SARS-CoV-2 Diagnostics. Lessons Learned from a Pandemic.

Since the 2019 novel coronavirus outbreak began in Wuhan, China, diagnostic methods in the field of molecular biology have been developing faster than ever under the vigilant eye of world's research community. Unfortunately, the medical community was not prepared for testing such large volumes or ranges of biological materials, whether blood samples for antibody immunological testing, or salivary/swab samples for real-time PCR. For this reason, many medical diagnostic laboratories have made the switch to working in the field of molecular biology, and research undertaken to speed up the flow of samples through laboratory. The aim of this narrative review is to evaluate the current literature on laboratory techniques for the diagnosis of SARS-CoV-2 infection available on pubmed.gov, Google Scholar, and according to the writers' knowledge and experience of the laboratory medicine. It assesses the available information in the field of molecular biology by comparing real-time PCR, LAMP technique, RNA sequencing, and immunological diagnostics, and examines the newest techniques along with their limitations for use in SARS-CoV-2 diagnostics.