Annual influenza vaccination is recommended in many parts of the world including Canada and USA. However, there is limited understanding on the effect of repeated influenza vaccination.
The issue that repeated influenza vaccination could have negative impact on vaccine performance was first noticed in 1970s. In a study on three outbreaks of influenza A in boys at a British boarding school in 1972 (A/England/42/72), in 1974 (A/Port Chalmers), and in 1976 (A/Victoria), Hoskins et al. demonstrated that vaccination in early seasons can have impact on the risk of influenza infection in future seasons 108. Another study from Australia at the same period of time showed that significant protection by IIV against A/Victoria/75 (H3N2) existed among …show more content…
Both IIVs and LAIVs have shown vaccine efficacy in healthy children (aged over 2 years) and adults. However, there is great discrepancy between vaccine efficacy and vaccine effectiveness with latter is significant lower than the former.
Although many countries have the national policies recommending annual vaccination for high risk groups such as young children aged 6 months to 2 years, elderly aged over 65, and pregnant women, there is surprisingly little evidence of high quality (i.e., RCTs) to support these policies. Another issue about annual vaccination is the negative impact of repeated vaccination. Almost four decades has passed since the issue was first raised in 1970s, it was still poorly understood in terms of immunologic mechanism and clinical significance. There is an urgent need to conduct adequate RCTs to address these problems.
Recent studies have shown indirect protectiveness of influenza vaccination in children and in healthcare workers in some but all settings. More research is needed to understand how indirect protectiveness could be achieved. Also, cost-effectiveness analysis of influenza vaccination programs should also take indirect benefits into
The issue that repeated influenza vaccination could have negative impact on vaccine performance was first noticed in 1970s. In a study on three outbreaks of influenza A in boys at a British boarding school in 1972 (A/England/42/72), in 1974 (A/Port Chalmers), and in 1976 (A/Victoria), Hoskins et al. demonstrated that vaccination in early seasons can have impact on the risk of influenza infection in future seasons 108. Another study from Australia at the same period of time showed that significant protection by IIV against A/Victoria/75 (H3N2) existed among …show more content…
Both IIVs and LAIVs have shown vaccine efficacy in healthy children (aged over 2 years) and adults. However, there is great discrepancy between vaccine efficacy and vaccine effectiveness with latter is significant lower than the former.
Although many countries have the national policies recommending annual vaccination for high risk groups such as young children aged 6 months to 2 years, elderly aged over 65, and pregnant women, there is surprisingly little evidence of high quality (i.e., RCTs) to support these policies. Another issue about annual vaccination is the negative impact of repeated vaccination. Almost four decades has passed since the issue was first raised in 1970s, it was still poorly understood in terms of immunologic mechanism and clinical significance. There is an urgent need to conduct adequate RCTs to address these problems.
Recent studies have shown indirect protectiveness of influenza vaccination in children and in healthcare workers in some but all settings. More research is needed to understand how indirect protectiveness could be achieved. Also, cost-effectiveness analysis of influenza vaccination programs should also take indirect benefits into