Potential infections of H5N1 and H9N2 avian influenza do exist in Guangdong populations of China

Background Southeast China is one of the sites of influenza origin. During 2003-2004, nine avian influenza outbreaks took place in Guangdong Province. But no human case was reported. To examine the status of potential human infection by human influenza （H1N1, H3N2） and avian influenza （H5N1, H7N7, H9N2） in the avian influenza epidemic area of Guangdong Province, China, we conducted a seroepidemiologic survey in the people of this area from April to June of 2004.Methods Three out of 9 H5N1 avian influenza affected poultry areas in Guangdong were randomly selected, and the population living within 3 kilometers of the affected poultries were chosen as the survey subjects. One thousand two hundred and fourteen people were selected from 3 villages at random. Human and avian influenza antibody titers were determined by hemagglutination-inhibition （HI） test and microneutralization test （MNT）. Results The positive rate of antibody to H5N1 was 3.03% in the occupational exposure group and 2.34% in general citizens group; that of H9N2 was 9.52% in the occupational exposure group and 3.76% in the general citizens group. Moreover one case in the occupational exposure group was positive for H7N7. One year later, all previously positive cases had become negative except for one H5N1-positive case. Conclusion The observations imply that H5N1 and H9N2 avian influenza silent infections exist in Guangdong populations.

Variation in SARS-CoV-2 seroprevalence in children in the region of Asturias,Northern Spain

Background Updated seroprevalence estimates are important to describe the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)landscape and to guide public health decisions.The aims are to describe longitudinal changes in seroprevalence in children in a region in Northern Spain and to analyze factors associated with SARS-CoV-2 seropositivity.Methods Prospective multicenter longitudinal study with subjects recruited from July to September 2020.Children(up to 14 years old)were included and followed up until September 2021.Venous blood samples were collected every six months during three testing rounds and were analyzed for SARS-CoV-2 antibodies.The data regarding epidemiological features,contact tracing,symptoms,and virological tests were collected.The evolution of SARS-CoV-2 seroprevalence during the study and the differences between children with positive and negative SARS-CoV-2 antibody tests were analyzed.Results Two hundred children were recruited(50.5%girls,median age 9.7 years).The overall seroprevalence increased from round 1[1.5%,95%confidence interval(CI)0.3%–4.3%]to round 2(9.1%,95%CI 4.6%–12.7%)and round 3(16.6%,95%CI 9.5%–19.6%)(P<0.001).Main changes occurred in children aged zero to four years(P=0.001)who lived in urban areas(P<0.001).None of the children who were previously positive became seronegative.Following multivariable analysis,three variables independently associated with SARS-CoV-2 seropositivity were identified:close contact with coronavirus disease 2019(COVID-19)confirmed or suspected cases[odds ratio(OR)=3.9,95%CI 1.2–12.5],previous positive virological test(OR=17.1,95%CI 3.7–78.3)and fatigue(OR=18.1,95%CI 1.7–193.4).Conclusions SARS-CoV-2 seroprevalence in children has remarkably increased during the time of our study.Fatigue was the only COVID-19-compatible symptom that was more frequent in seropositive than in seronegative children.

Low SARS-CoV-2 seroprevalence but high perception of risk among healthcare workers at children’s hospital before second pandemic wave in Germany

Background Healthcare workers are considered a particularly high-risk group during the coronavirus disease 2019(COVID-19)pandemic.Healthcare workers in paediatries are a unique subgroup:they come into frequent contact with children,who often experience few or no symptoms when infected with severe acute respiratory syndrome coronavirus 2(SARS CoV-2)and,therefore,may transmit the disease to unprotected staff.In Germany,no studies exist evaluating the risk of COVID-19 to healthcare workers in paediatric institutions.Methods We tested the staff at a large children's hospital in Germany for immunoglobulin(Ig)G antibodies against the nucle-ocapsid protein of SARS CoV-2 in a period between the first and second epidemic wave in Germany.We used a questionnaire to assess each individual's exposure risk and his/her own perception of having already been infected with SARS-CoV-2.Results We recruited 619 participants from all sectors,clinical and non-clinical,constituting 70%of the entire staff.The seroprevalence of SARS CoV-2 antibodies was 0.325%(95%confidence interval 0.039-I.168).Self-perceived risk of a previ-ous SARS-CoV-2 infection decreased with age(odds ratio,0.81;95%confidence interval,0.70-0.93).Having experienced symptoms more than doubled the odds of a high self-perceived risk(odds ratio,2.18;95%confidence interval,1.59--3.00).There was no significant difference in self perceived risk between men and women.Conclusions Seroprevalence was low among healtheare workers at a large children's hospital in Germany before the second epidemic wave,and it was far from a level that confers herd immunity.Self-perceived risk of infection is often overestimated.