Background Little is known about the nature and durability of the humoral immune response to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods We measured antibodies in serum samples from 30,576 persons in Iceland, using six assays (including two pan-immunoglobulin [pan-Ig] assays), and we determined that the appropriate measure of seropositivity was a positive result with both pan-Ig assays. We tested 2102 samples collected from 1237 persons up to 4 months after diagnosis by a quantitative polymerase-chain-reaction (qPCR) assay. We measured antibodies in 4222 quarantined persons who had been exposed to SARS-CoV-2 and in 23,452 persons not known to have been exposed. Results Of the 1797 persons who had recovered from SARS-CoV-2 infection, 1107 of the 1215 who were tested (91.1%) were seropositive; antiviral antibody titers assayed by two pan-Ig assays increased during 2 months after diagnosis by qPCR and remained on a plateau for the remainder of the study. Of quarantined persons, 2.3% were seropositive; of those with unknown exposure, 0.3% were positive. We estimate that 0.9% of Icelanders were infected with SARS-CoV-2 and that the infection was fatal in 0.3%. We also estimate that 56% of all SARS-CoV-2 infections in Iceland had been diagnosed with qPCR, 14% had occurred in quarantined persons who had not been tested with qPCR (or who had not received a positive result, if tested), and 30% had occurred in persons outside quarantine and not tested with qPCR. Conclusions Our results indicate that antiviral antibodies against SARS-CoV-2 did not decline within 4 months after diagnosis. We estimate that the risk of death from infection was 0.3% and that 44% of persons infected with SARS-CoV-2 in Iceland were not diagnosed by qPCR.

Following the report of a non-travel-associated cluster of monkeypox cases by the United Kingdom in May 2022, 41 countries across the WHO European Region have reported 21,098 cases and two deaths by 23 August 2022. Nowcasting suggests a plateauing in case notifications. Most cases (97%) are MSM, with atypical rash-illness presentation. Spread is mainly through close contact during sexual activities. Few cases are reported among women and children. Targeted interventions of at-risk groups are needed to stop further transmission.

Key Points• Obesity is not associated with MGUS or LC-MGUS.• High body mass index during midlife is associated with increased risk of progressing from MGUS and LC-MGUS to MM and other LP diseases.All multiple myeloma (MM) cases are preceded by the premalignant state monoclonal gammopathy of undetermined significance (MGUS). Results from previous studies show a positive association between obesity and MM; however, the association between obesity and MGUS is controversial. The aims were to determine (1) if obesity is associated with an increased risk of MGUS and light-chain MGUS (LC-MGUS) and (2) whether obesity is associated with a higher risk of progression to MM and other lymphoproliferative (LP) diseases. Data from the population-based Age, Gene/Environment Susceptibility-Reykjavik Study (N 5 5764) were used. We performed serum protein electrophoresis and serum free light-chain assay on all subjects to identify MGUS and LC-MGUS cases. We included 11 different measures on current and previous obesity in our analysis. Logistic regression andCox proportional-hazard regression were used to analyze the associations. A total of 300 (5.2%) MGUS and 275 (4.8%) LC-MGUS cases were identified. During a median follow-up of 8 years, 18 had progressed to MM and 11 to other LP diseases. We found no association between the 11 obesity markers and MGUS or LC-MGUS (odds ratios 0.81 to 1.15 for all 11 variables in both conditions). Interestingly, we found that high midlife body mass index increased risk of progression to MM and other LP diseases (hazard ratio, 2.66; 95% confidence interval, 1.17-6.05). To conclude, obesity was not associated with MGUS. However, we found overweight/obesity to be a risk factor for progression from MGUS to MM and other LP diseases, suggesting that obesity plays a role in the transformation of MGUS to MM.