Natural or vaccine-induced antibody as a predictor of immunity in the face of natural challenge with influenza viruses

Abstract

SUMMARYA study of influenza in residential schools provided the opportunity to assess the significance of antibody as a predictor of immunity. Five hundred and fifty-six pupils from 8 schools were included in the investigations, and the outcome for these children in 27 naturally occurring outbreaks of influenza was analysed. The outbreaks comprised 5 caused by strains of influenza A H3N2, 10 caused by strains of influenza A HIN1, and 12 caused by strains of influenza B. On 8 occasions a second outbreak of the same serotype occurred in a school.There was a general correlation between the presence of antibody to the outbreak strain and protection from infection. For each of the three influenza virus serotypes the infection rate in those with no detectable antibody was approximately 80 %. Those with past experience of the virus but no antibody to the outbreak strain experienced lower infection rates (62 % overall) but the infection rates were lowest in those with intermediate and high level antibody to the challenge strain (18% overall).Vaccine was used by three of the schools. The effect of antibody derived from recent experience, either natural or vaccine-induced, on subsequent challenge with a drifted strain i.e. one showing antigenic drift away from the previous strain, was compared. Intermediate or 'high level antibody to the challenge strain in those who had experienced a recent natural infection was associated with a low infection rate (9%). A similar level of antibody produced in response to vaccination was associated with a significantly higher infection rate (23 %: P < 0-025). Among the vaccinees who had produced such antibody the infection rate was highest (32 %) in those who had responded to vaccine in the presence of antibody to the vaccine strain.

Moderate influenza vaccine effectiveness against hospitalisation with A(H3N2) and A(H1N1) influenza in 2013–14: Results from the InNHOVE network

“…This approach, widely used and validated among GP based IVE studies, assumes that, by recruiting patients presenting with the same syndrome, we are likely to minimise selection biases [16][17][18]. In our study, A(H3N2) cases were of similar age as controls but tended to have less chronic diseases (non-significant differences).…”

“…15,16 Recent past natural infections may play a booster role on the immunological response to seasonal vaccination. 17,18 Immune senescence 4 and a lower incidence of A(H1N1)pdm09 among elderly since the 2009 pandemic could partially explain the lower IVE against this subtype observed among patients. The higher IVE against A(H3N2) among elderly would require further investigation as it is in contradiction with the principles of immune senescence.…”

Evaluating the case for trivalent or quadrivalent influenza vaccines

“…Correlation between antibody levels (as measured by haemagglutination-inhibition [HI] titres) and protection against clinical disease is limited but the results of challenge studies with attenuated viruses and natural experiments during wild disease outbreaks suggest that HI antibody titres of 1:40 are associated with protection from influenza illness in up to 50% of subjects. 25,26 Influenza vaccine programmes Influenza vaccination programmes vary depending on the country -the UK operates one with both selective and universal components. The selective program provides protection for individuals at higher risk of infection -these include those aged 6 months to 64 years with chronic lung, heart, renal, liver and neurological conditions, the immunocompromised, people with diabetes, individuals with asplenia or hyposplenia and pregnant women.…”

“…Furthermore, high antibody titres have been shown to prevent disease whereas lower titres modify disease severity. 1,26,27 In adults, neutralising antibodies to HA appear within about 7 days. Given that the majority will have been previously exposed to the same or similar epitopes through earlier infection, this is the response of primed individuals so the time to respond in na€ ıve children may be different and presumably longer.…”

Concurrent outbreaks of influenza and parvovirus B19 in a boys' boarding school

“…Previous studies in school-children have shown that during influenza outbreaks a clinical diagnosis of influenza is confirmed in the laboratory in approximately 90% of cases (1). In the spring term of 1985 there was an outbreak of clinical influenza-like illness at Christ's Hospital, a boarding school in Sussex which then numbered some 675 boys aged 11-18 years.…”