Influenza surveillance in England and Wales: November 1990--June 1991.
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Cross-Sectional Studies↗
Biomedical subjects
P Chakraverty
Publications and source records attributed to P Chakraverty.
Serological responses in volunteers to inactivated trivalent subunit influenza vaccine: antibody reactivity with epidemic influenza A and B strains and evidence of a rapid immune response.
A study of the immunogenicity of the inactivated trivalent subunit influenza vaccine for the 1989/90 season was performed in what proved to be an influenza epidemic year. One hundred student volunteers at The London Hospital Medical College participated in the study and the findings indicated that there was an excellent serological match between the epidemic strain of influenza A (H3N2) and the vaccine strain. Before vaccination, the geometric mean titre (GMT) to A/England/308/89, a representative H3N2 epidemic strain in the United Kingdom from the 1989/90 season, was 46. Post-vaccination the antibody levels rose and 99% of vaccinees had HI titres of greater than or equal to 40, the GMT being 131. The serological responses were also investigated against other circulating influenza A (H3N2 and H1N1) and B strains. Preliminary results of an evaluation of the rapidity of the immune response showed that in three of six subjects rises in HI antibody appeared within two days of vaccination.
Adult↗
An unusual community outbreak of influenza A.
The Hong Kong H3N2 subtype of influenza A virus appeared in 1968 and since then has caused epidemics of varying degrees of severity. We describe a community outbreak of influenza A H3N2 which occurred in members of a bowls club in an English rural village in late April 1989. The explosive onset, high attack rate (34/41 = 83 per cent) in those exposed, and the clinical presentation initially suggested a toxic or allergic aetiology. Twenty-three persons consulted their general practitioners; before the diagnosis was made all cases were considered to merit antibiotic therapy and 17/23 were prescribed steroids or bronchodilators on account of persisting severe wheeze and chest tightness. One of the 23 was admitted to hospital. There were no deaths. Influenza vaccination is recommended for people at special risk but protective efficacy is relatively low and short-lived. Only two of the group had received influenza vaccination since the beginning of October 1988 and both became symptomatic. The use of amantadine for the prevention and early treatment of influenza A in selected situations merits serious consideration, provided the diagnosis is made sufficiently early.
Aged↗
Failure of influenza vaccine to prevent two successive outbreaks of influenza A H1N1 in a school community.
Forty nine of the 149 boys (33%) at a preparatory school fell ill at the beginning of the autumn term 1986 with symptoms of influenza. One hundred and eighty two of the 470 pupils (39%) in the senior part of the same school had similar symptoms of influenza at the beginning of the spring term 1987. A new variant of influenza A H1N1 virus was isolated from both outbreaks and shown to be antigenically similar to A/Taiwan/1/86. The attack rate among pupils who had previously received trivalent influenza vaccine containing A/Chile/1/83 H1N1 antigen was not significantly different from the rate among those who had never been vaccinated. It is concluded that annual vaccination of all boarding school pupils may be inappropriate.
Disease Outbreaks↗
Influenza in the United Kingdom 1982-85.
Influenza surveillance in the UK between the years 1982 and 1985 has demonstrated the regular winter appearance of influenza A virus of both H1N1 and H3N2 subtypes and influenza B. Their antigenic diversity is described and correlated with the national statistics for morbidity and mortality for influenza. One unexpected finding has been that despite the wide circulation of influenza viruses there has been a continuation of winters without significant increases in influenza deaths or morbidity. A previous report of influenza surveillance (Pereira & Chakraverty, 1982) noted an already unusual series of three consecutive winters with this pattern. This report records a further 4 years bringing a total of seven successive winters without evidence of epidemics of severe disease associated with influenza viruses, as indicated by the national UK statistics.
Antibodies, Monoclonal↗
The use of monoclonal antibodies for the antigenic analysis of influenza A viruses.
Monoclonal antibodies have been found to provide useful additional information for the antigenic analysis of influenza A viruses of the H3N2 and H1N1 subtypes. They have been particularly useful in the interpandemic period when multiple variants circulate concurrently.Apparently heterogeneous isolates can be placed in fairly clear-cut groups on the basis of their reactivity with certain monoclonal antibody preparations. It is thought likely that variants reacting with the least number of monoclones are the most different antigenically from the fully reactive strains.
Antibodies, Monoclonal↗
Influenza C virus in the United Kingdom.
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Child, Preschool↗
Influenza in the United Kingdom 1977-1981.
The laboratory surveillance of influenza in the UK has continued to demonstrate the regularity of influenza outbreaks each winter even in the absence of increase in the other indices which reflect the morbidity and mortality associated with influenza. The period of five years from 1976 to 1981 has seen the appearance of a second sub-type of influenza. A with the return of the historic H1N1 virus; and the continued circulation of H3N2 concurrently with H1N1 virus. Variants of both these influenza A viruses have been demonstrated as well as further changes in the strains of influenza B virus isolated during this time.
Antibodies, Viral↗
The return of the historic influenza A H1N1 virus and its impact on the population of the United Kingdom.
The epidemiology in the United Kingdom of the influenza A H1N1 subtype which returned in 1977 after an absence of 20 years in described for the four winter seasons from 1977/8 to 1980/1. The age distribution of virus isolates and the evidence for antigenic variation is presented. The impact in the susceptible age groups year by year is shown by the change in the population with specific antibody. There was the expected increase of antibody in those under the age of 21 but also evidence for a significant amount of infection or re-infection in the older adult population.
Adolescent↗
Comparison of haemagglutination-inhibition and single-radial-haemolysis techniques for detection of antibodies to influenza B virus.
Some of the strains influenza B isolated between 1975 to 1978 showed a significant drift away from the prototype strain B/HK/8/73 when tested by cross haemagglutination-inhibition. A serum survey for antibody to two strains of influenza B virus was carried out comparing haemagglutination-inhibition (HI) and single-radical haemolysis (SRH) tests. The SRH technique was found to be more sensitive than the HI test.
Adolescent↗
Antigenic relationship between influenza C viruses.
The object of this study was to determine whether antigenic groupings exist among influenza C viruses. Altogether seven influenza type C strains were examined by reciprocal haemagglutination-inhibition and serum neutralization tests with sera produced in ferrets. Some biological properties were also compared and differences were found in their ability to agglutinate erythrocytes from various species, in their ability to adsorb onto rat and fowl erythrocytes, and in their rates of elution from the cells. The results obtained using these techniques confirmed that antigenic variation exists among influenza C viruses although it is not as clear cut as among influenza A viruses. This was supported by the results of a serological survey of antibody in different age groups.
Animals↗
The laboratory surveillance of influenza epidemics in the United Kingdom 1968-1976.
The extensive laboratory investigations of respiratory disease in the U.K. over many years have demonstrated the frequency with which influenza viruses, both A and B, are found each winter. Only rarely are none isolated. These findings correlate well with other indicators of influenza such as increases in sickness benefit claims and in deaths attributed to influenza and pneumonia. However, outside these demonstrable peaks of incidence influenza viruses have been found to circulate over considerably longer periods often first appearing as early as November and continuing through to April or even May. But there has been no regular or predictable pattern determined. The period of 1968-76 has seen a series of differently developing influenza winter epidemics caused by a series of the H3N2 virus. The contributions of virus isolation and serology to influenza surveillance is discussed.
Antibodies, Viral↗
Single-radial-hemolysis: a new method for the assay of antibody to influenza haemagglutinin. Applications for diagnosis and seroepidemiologic surveillance of influenza.
A simple single-radial-haemolysis technique is described that permits the detection and assay of antibody to influenza virus haemagglutinin. The method depends on the passive haemolysis of virus-treated erythrocytes by antihaemagglutinin antibody and complement. Under the "standard" test conditions described antibody to the other surface antigen of the influenza virus (neuraminidase) or to the internal antigens of the virus (nucleoprotein and matrix protein) do not produce haemolysis. Because it requires only small amounts of crude virus antigen and is rapid and simple, the method appears to be of considerable value for large-scale seroepidemiologic studies of new influenza virus variants. Antihaemagglutinin antibody detected by single-radial-haemolysis appears to be relatively strain-specific; the technique may therefore be useful in the antigenic characterization of virus isolates.
Antibodies, Viral↗
The detection and multiplication of influenza C virus in tissue culture.
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Animals↗
Antigenic variation in current influenza A viruses: evidence for a high frequency of antigenic 'drift' for the Hong Kong virus.
A new antigenic variant of the Hong Kong (H3N2) subtype of influenzavirus type A is described. The variant, A/Port Chalmers/1/73 (H3N2), was first isolated in Australasia in the autumn of 1973 and subsequently became the predominant influenza A variant in most areas of the world, replacing the previously prevalent strain A/England/42/72 (H3N2). The 1973 variant shows antigenic differences from former Hong Kong variants in both haemagglutinin and neuraminidase antigens. The application of immuno-double-diffusion tests and single-radial-diffusion tests in the antigenic analysis of new variants of the influenzavirus is also described. It is emphasized that since new variants of the Hong Kong virus have appeared in the successive years 1971, 1972, and 1973, the annual frequency of antigenic "drift" for the Hong Kong virus is higher than was recorded for the "Asian" influenzavirus (H2N2) in the first 5 years of the latter's prevalence from 1957 to 1962, during which period little antigenic variation occurred.
Antibodies, Viral↗
Antigenic variants of influenza B virus.
From 1967 to 1971 little antigenic variation was detected in the prevalent influenza B viruses but in December 1972 a new antigenic variant of influenza B was isolated in Hong Kong from sporadic cases of influenza. The new variant, B/Hong Kong/5/72, possessed a haemagglutinin antigen which showed considerable antigenic differences from that of former influenza B strains while its neuraminidase antigen was closely related to that of the earlier, 1967-71, isolates. The B/Hong Kong/5/72 variant became the predominant influenza B strain in the United Kingdom by early summer 1973, and in both the United Kingdom and Japan this strain was associated with outbreaks of influenza. Strains antigenically intermediate between the 1967-71 isolates and B/Hong Kong/5/72 were isolated in a number of countries, often concurrently with B/Hong Kong/5/72-like strains.Serological studies indicated that antibody to B/Hong Kong/5/72 was infrequent in the populations in the United Kingdom and the U.S.A., suggesting the possibility of future epidemic activity associated with the new variant. In addition, conventional inactivated influenza vaccines containing the older influenza B isolates given to volunteers stimulated poor antibody responses to B/Hong Kong/5/72 virus. These studies indicate the desirability of immunizing high risk patients against B/Hong Kong/5/72-like viruses before the coming influenza season. Vaccine containing the new variant influenza B strain are currently available in the United Kingdom.
Antibodies, Viral↗
Hong Kong influenza in the Royal Air Force 1968-70.
A prospective serological and clinical study of the epidemics due to the A2/Hong Kong/68 influenza virus was made during the winters 1968-9 and 1969-70 in volunteer subjects in the Royal Air Force. In October 1968 nearly all subjects had haemagglutination inhibiting (HI) antibody to the A2/Singapore/57 virus and more than half had antibody to strains more recently prevalent in Britain. The proportion with HI antibody to A2/Hong Kong/68 increased from 31% in October 1968 (most at low titres) to 44% after the first epidemic and 72% after the second (most at high titres). Serological infection rates were much lower in those who had detectable antibody at the beginning of each winter than in those who did not. Respiratory illnesses coupled with serological evidence of influenza infection during the winter were rare in persons with an initial titre of HI antibody of 1/40 or more. Infection in the first winter conferred complete protection against infection, with or without illness, in the second. In both epidemics about half those with serological evidence of infection had no reported illness.
Adolescent↗
Antigenic variation in current human type A influenza viruses: antigenic characteristics of the variants and their geographic distribution.
Outbreaks of influenza due to the virus A/Hong Kong/1/68 (H3N2) began in 1968 and are still occurring. The haemagglutinin of this virus is different from that of the A/Singapore/1/57 virus (the "Asian" strain) but the neuraminidase antigens are the same. Between 1968 and 1971 only minor antigenic "drift" in the haemagglutinin was noted, but in recent months 2 isolates have been identified in which considerable "drift" has occurred in the haemagglutinin and in the neuraminidase antigens. One, A/Hong Kong/5/72 (H3N2), was first detected in outbreaks in Hong Kong between November 1971 and January 1972 and was predominant there and in Korea but did not become widely disseminated. The second strain, A/England/42/72 (H3N2), has been isolated in winter outbreaks in the southern hemisphere and now appears to be the predominant strain in the northern hemisphere. The characteristics of the strains are described.
Africa↗