Antigenic and molecular analysis of influenza A (H3N2) virus strains isolated from a localised influenza outbreak in South Africa in 2003

Abstract

A severe acute institutional influenza outbreak occurred in a police residential college in Pretoria amongst new recruits and staff members at the end of May 2003. The outbreak was characterised by marked illness which affected a total of 648 students, 26 of whom were admitted to hospital. Symptoms included pyrexia, severe headache, and myalgia. The attack rate per dormitory building ranged from 20 to 47%, with an overall attack rate of 34%. Throat swabs and bronchoalveolar lavage specimens were sent to the National Institute for Communicable Diseases (NICD) from 20 patients. All were positive for influenza A by multiplex PCR and/or indirect immunofluorescence, and were further identified as subtype H3N2. Additional specimens from sporadic influenza cases in Johannesburg and surrounding areas were collected through the NICD active viral surveillance programme for respiratory viral testing and were also positive for influenza A H3N2 viruses. Viruses isolated from patients from both the institutional outbreak as well as from sporadic cases were analysed both antigenically and at the molecular level to determine the characteristics of the influenza strain responsible for the epidemic. The results showed clearly that the outbreak was caused by the introduction in 2003 into South Africa of the novel A/Fujian/411/02-like H3N2 influenza strain, which is antigenically distinct from the A/Panama/2007/99 vaccine strain. The rapid spread of these variant viruses to the southern hemisphere indicates that the H3N2 component of the influenza vaccine needs to be updated for the 2004 southern hemisphere winter.

Genetic Analysis of Influenza A/H3N2 and A/H1N1 Viruses Circulating in Vietnam from 2001 to 2006

“…RNA was transcribed to cDNA with the influenza A virus universal primer Uni12, as described elsewhere (24). The HA genes (segment 4), the NA genes (segment 6), and the M genes (segment 7) of H1N1 and H3N2 viruses were amplified with segment-specific primers as described elsewhere (3,24).…”

Cellular and Humoral Responses to Influenza in Gabonese Children Living in Rural and Semi‐Urban Areas

“…Sporadic monitoring of influenza in other African countries has revealed outbreaks of H3N2 virus in South Africa in 2003 [28], in Madagascar in 2002 [2], and in the Democratic Republic of Congo in 2002 [2]. In addition, influenza B viruses have been reported to be circulating in South Africa, Madagascar, and Kenya [29,30].…”

A call to cellular & humoral arms: Enlisting cognate T cell help to develop broad-spectrum vaccines against influenza A

“…33 A 2006 Cochrane review of 64 studies published between 1974 and 2004 found that in homes for the elderly (with good influenza vaccine match and high viral circulation) the effectiveness of vaccines against influenza-like illness was only 23% (95% confidence interval 6% to 36%) and non-significant against influenza (RR 1.04: 95% confidence interval 0.43 to 2.51). 34 How 35 The serologic response to influenza virus vaccine also varies with the age of the recipient and previous exposure to influenza virus. 36 In primed individuals (those who have had previous exposure to influenza), vaccination with CIV induces "protective" levels of antibody against HA, which prevent infection in 89% of recipients shortly after vaccination.…”