Synopsis and Appraisal of a Study on the Effectiveness of Influenza Vaccine on Type of Virus and Age of the Patients
The purpose of this paper is to summarize and appraise a research study conducted in the United States on the observation of the year 2012 – 2013, which focused on the effectiveness of the Influenza vaccine on the type of the virus and the age of the patient with acute cough. According to the US Flu VE Network, the Influenza vaccine worked well in the first four weeks of 2012-2013, but it showed more mortality than the previous Influenza seasons. It was found that the cocirculation of influenza A(H3N2), influenza B Yamagata and influenza B/Victoria was the cause of ineffectiveness if the vaccine. CDC focused on the measurement of the effectiveness of the vaccine by its types and subtypes and by the age of the patients. The vaccine was moderately effective in certain age groups, but they need to be effective in order t stop the mortality due to influenza. The VE then predicted if there is any need to alter the vaccines or not. VE of the subjects who were vaccinated the prior year also estimated the residual efficacy of the vaccine. It is an essential step towards the vaccine’s effectiveness to know which types and subtypes of the virus will be useful and to find out if the vaccine can leave residual vaccine, which shows any efficacy in the next year.
Summary of the Study
The VE for influenza has been investigated since 2004- 2005, but the death rates were high in 2012-2013 due to the cocirculation of influenza virus with its subtypes. It was estimated that to an effective vaccine for the virus, there needs research to be conducted based on types and subtypes of the virus along with the age group of patients. This study will lead to an effective vaccine formulation for the state. The primary reason behind studying the age group and subtypes of the virus is that the onset and enrollment of different types and subtypes of the influenza virus are varied with age group as well as kind and subtype.
Patients ranging ≥from 6 months to ≥65 years who had acute cough illness and were seeking outpatient medical care were enlisted in five states of the US for testing. The swab was taken from the patients with their vaccination dates noted to calculate VE. The samples were taken from the patients who had an acute respiratory infection with a cough for more than seven days and have not received any antiviral medication yet. The five states were Texas, Southeastern Michigan, Pittsburg, Temple-Belton, and Pennsylvania. The patients completed an interview regarding the symptoms, their demographic characteristics, and the health Patients with a healthcare problem in the last year. This will call for a high-risk condition in the patient. The children from 6 months of age to 8 years were eligible if they had received the number of doses as recommended by ACIP (Advisory community of Immunization practices.). The patients who had received their vaccine in 24 days before or have not completed their immunization by ACIP. 4 vaccine exposure groups were made, namely 1—vaccinated in the current and prior statement.2.vaccinated in the current season3—protected in the last season 4—not vaccinated in both seasons.
Appraisal
The logistic regression model was used to estimate odds ratios compare between vaccinated and unvaccinated patients. VE was calculated for the licensed vaccines, which are IIV3 and LAIV3. But estimation of LAIV3 is restricted because LAIV3 is less in adults. The VE models had high-risk health status, age, network site, and calendar time. VE was estimated by two alternative means of representing vaccination status. Out of 6452 patients involved in the analysis, 36% (2307) tested positive for the test, among which 60% were affected by the influenza A virus, and 30% were affected by the influenza B virus. The cases where subtype of the virus was determined in 1292 had influenza A (H3N2), 582 were influenza B Yamagata, and 303 were having influenza B/Victoria. Seven patients had got coinfections with influenza A and B. while three had coinfection of both B influenza. The difference in effectiveness between Influenza A(H3N2) and Influenza B was found minimal. The studies showed significant protection against Influenza A(H3N2) for the patients of age groups six months- 8 years, 18 -49 years, and 50 – 64. VE is lower among the age groups 9 -17 and 18 -49 in which only residual effects of the prior vaccine were observed. Whereas, in adults of the age group 50 -64, the residual effect of the vaccine only was not found. VE against influenza was highest in age groups six months to 17 years and 50 -64, and it was the lowest against the ones who are more than 60 years of age.
Conclusion
According to the study carried out in 2012-2013, the vaccines were moderately effective in most of the age groups. The cross-infection and residual effects from prior vaccination were taken into consideration. In the younger age groups, there was residual protection from the last year’s vaccine. The vaccine protects against influenza A (H3N2) and Influenza B. Significant protection was observed against all age groups except for the ones who are more than or equal to 65 years. A vaccine with a trivalent vaccine was effected against the influenza B virus. The studies showed that the licensed quadrivalent vaccines were not as effective as the trivalent vaccine. Residual protection may have varied the results of VE.
Further studies are required to understand the immunologic effects of repeated vaccination. Seasonal VE estimates should be reported by virus type, subtype, lineage, and vaccine types to facilitate the comparisons. A cost useful study also needs to be carried out to find out the effects of repeated seasonal vaccine.