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A study was conducted to compare the efficacy of inactivated as against live attenuated influenza vaccines. Results indicated that inactivated vaccines were more effective in preventing symptomatic influenza A in healthy adults, and was also more effective than live attenuated vaccines.

A randomized noninferiority trial designed to compare the efficacy of hepatitis A vaccine with that of immune globulin for prophylaxis after household or day-care exposure to hepatitis A is presented. Hepatitis A vaccine is found to provide long-term immunity and might be a reasonable choice for postexposure prophylaxis.

A clinical trial is carried out to determine the efficacy as measured by laboratory confirmation of influenza, of both the inactivated and live attenuated influenza vaccines in the healthy adult population during the influenza season. It is observed that the inactivated and live attenuated influenza vaccines are efficacious in preventing laboratory-confirmed symptomatic illnesses from influenza in healthy adults but the live attenuated vaccines are less efficacious.

We studied nonpharmaceutical interventions used to mitigate the second, and most deadly, wave of the 1918-1920 influenza pandemic in the United States. We conclude that several small communities implemented potentially [...]

While measures such as closing schools and social distancing may slow the effects of pandemic influenza, only vaccines and antiviral drugs are clearly efficacious in preventing infection or treating illness. [...]

Background. Trivalent inactivated influenza vaccine (TIV) is recommended for all children ages 6 to 23 months. Delivering 2 doses of TIV at least 4 weeks apart to young children receiving this vaccine for the first time is challenging. Methods. We compared the immunogenicity and reactogenicity of the standard 2-dose regimen of TIV administered in the fall with an early schedule of a single spring dose followed by a fall dose of the same vaccine in healthy toddlers 6 to 23 months of age. Children were recruited in the spring to be randomized into either the standard or early schedule. An additional group was also enrolled in the fall as part of a nonrandomized standard comparison group. The 2002-2003 licensed TIV was administered in the spring; the fall 2003-2004 vaccine contained the same 3 antigenic components. Reactogenicity was assessed by parental diaries and telephone surveillance. Blood was obtained after the second dose of TIV for all children. The primary outcome measure was antibody response to influenza A/HIN1, A/H3N2, and B after 2 doses of vaccine, as determined by hemagglutination-inhibition titers [greater than or equal to] 1:32 and geometric mean titer (GMT). Results. Two hundred nineteen children were randomized to receive either the standard or early TIV schedule; 40 additional children were enrolled in the fall in the nonrandomized standard group. Response rates in the combined standard versus early groups were similar overall: 78% (GMT: 48) vs 76% (GMT: 57) to HIN1, 89% (GMT: 115) vs 88% (GMT: 129) to H3N2, and 52% (GMT: 24) vs 60% (GMT: 28) to B. Reactogenicity after TIV in both groups of children was minimal and did not differ by dose, age, or time between doses. Reaction rates were higher in those receiving TIV and concomitant vaccines compared with those receiving TIV alone. Overall rates of fever >38[degrees]C axillary and injection-site pain, redness, or swelling were 5.4%, 3.1%, 0.9%, and 1.1%, respectively. Conclusions. When the spring and fall influenza vaccines had the same 3 antigenic components, the early vaccine schedule resulted in similar immunogenicity and reactogenicity compared with the standard schedule. When the vaccine components do not change between years, initiating influenza vaccine in the spring at the time of routine office visits would facilitate full immunization of children against influenza earlier in the season. Pediatrics 2005;115:1039-1047; inactivated influenza vaccine, children., ABBREVIATIONS. TIV, trivalent inactivated influenza vaccine; CI, confidence interval; HAI, hemagglutination-inhibition; GMT, geometric mean titer. Trivalent inactivated influenza vaccine (TIV) has been demonstrated to be safe and effective in children [...]

Introduction: In Southeast Michigan, active surveillance studies monitor influenza activity in hospitals, ambulatory clinics, and community households. Across five respiratory seasons, we assessed the contribution of data from each of the three networks towards improving our overall understanding of regional influenza circulation. Methods: All three networks used case definitions for acute respiratory illness (ARI) and molecularly tested for influenza from research‐collected respiratory specimens. Age‐ and network‐stratified epidemic curves were created for influenza A and B. We compared stratified epidemic curves visually and by centering at seasonal midpoints. Results: Across all seasons (from 2014/2015 through 2018/2019), epidemic curves from each of the three networks were comparable in terms of both timing and magnitude. Small discrepancies in epidemics recorded by each network support previous conclusions about broader characteristics of particular influenza seasons. Conclusion: Influenza surveillance systems based in hospital, ambulatory clinic, and community household settings appear to provide largely similar information regarding regional epidemic activity. Together, multiple levels of influenza surveillance provide a detailed view of regional influenza epidemics, but a single surveillance system—regardless of population subgroup monitored—appears to be sufficient in providing vital information regarding community influenza epidemics. [ABSTRACT FROM AUTHOR]

Background Evidence for vaccine effectiveness (VE) against influenza-associated pneumonia has varied by season, location, and strain. We estimate VE against hospitalization for radiographically identified influenza-associated pneumonia during 2015–2016 to 2017–2018 seasons in the US Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN). Methods Among adults aged ≥18 years admitted to 10 US hospitals for acute respiratory illness (ARI), clinician-investigators used keywords from reports of chest imaging performed during 3 days around hospital admission to assign a diagnosis of "definite/probable pneumonia." We used a test-negative design to estimate VE against hospitalization for radiographically identified laboratory-confirmed influenza-associated pneumonia, comparing reverse transcriptase–polymerase chain reaction–confirmed influenza cases with test-negative subjects. Influenza vaccination status was documented in immunization records or self-reported, including date and location. Multivariable logistic regression models were used to adjust for age, site, season, calendar-time, and other factors. Results Of 4843 adults hospitalized with ARI included in the primary analysis, 266 (5.5%) had "definite/probable pneumonia" and confirmed influenza. Adjusted VE against hospitalization for any radiographically confirmed influenza-associated pneumonia was 38% (95% confidence interval [CI], 17–53%); by type/subtype, it was 74% (95% CI, 52–87%) influenza A (H1N1)pdm09, 25% (95% CI, −15% to 50%) A (H3N2), and 23% (95% CI, −32% to 54%) influenza B. Adjusted VE against intensive care for any influenza was 57% (95% CI, 19–77%). Conclusions Influenza vaccination was modestly effective among adults in preventing hospitalizations and the need for intensive care associated with influenza pneumonia. VE was significantly higher against A (H1N1)pdm09 and was low against A (H3N2) and B. [ABSTRACT FROM AUTHOR]

The drug zanamivir can prevent influenza in people who come in contact with infected individuals and can also shorten the duration of illness in infected people. This was the conclusion of a study of 337 families in which one member contracted the flu.

Intraseason timing of influenza infection among persons of different ages could reflect relative contributions to propagation of seasonal epidemics and has not been examined among ambulatory patients. Using data from the US Influenza Vaccine Effectiveness Network, we calculated risk ratios derived from comparing weekly numbers of influenza cases prepeak with those postpeak during the 2010–2011 through 2018–2019 influenza seasons. We sought to determine age-specific differences during the ascent versus descent of an influenza season by influenza virus type and subtype. We estimated 95% credible intervals around the risk ratios using Bayesian joint posterior sampling of weekly cases. Our population consisted of ambulatory patients with laboratory-confirmed influenza who enrolled in an influenza vaccine effectiveness study at 5 US sites during 9 influenza seasons after the 2009 influenza A virus subtype H1N1 (H1N1) pandemic. We observed that young children aged <5 years tended to more often be infected with H1N1 during the prepeak period, while adults aged ≥65 years tended to more often be infected with H1N1 during the postpeak period. However, for influenza A virus subtype H3N2, children aged <5 years were more often infected during the postpeak period. These results may reflect a contribution of different age groups to seasonal spread, which may differ by influenza virus type and subtype. [ABSTRACT FROM AUTHOR]

Prompt antiviral treatment has the potential to reduce influenza virus transmission to close contacts, but rigorous data on the magnitude of treatment effects on transmission are limited. Animal model data indicate that rapid reductions in viral replication after antiviral treatment reduce the risk of transmission. Observational and clinical trial data with oseltamivir and other neuraminidase inhibitors indicate that prompt treatment of household index patients seems to reduce the risk of illness in contacts, although the magnitude of the reported effects has varied widely across studies. In addition, the potential risk of transmitting drug-resistant variants exists with all approved classes of influenza antivirals. A controlled trial examining baloxavir treatment efficacy to reduce transmission, including the risk of transmitting virus with reduced baloxavir susceptibility, is currently in progress. If reduced transmission risk is confirmed, modeling studies indicate that early treatment could have major epidemiologic benefits in seasonal and pandemic influenza. [ABSTRACT FROM AUTHOR]