Dear readers, Peace be upon you all!
This post comes in reply for what was published recently by, Rogier Bodewes and colleagues (Yearly influenza vaccinations: a double-edged sword?) urging “re-evaluation of vaccine recommendations because the inactivated vaccine available at present does not induce heterosubtypic immunity and might make infants more susceptible to pandemic influenza.”1,
and before reading the reply, it would worth mentioning that heterosubtypic immunity is an immunity that is cross-protective between different influenza A virus subtypes
a reply came recently in the Lancet,
“… Bodewes and colleagues’ concern is primarily on the basis of their recent animal experiment.1, In animal studies, the investigators have full control over any environmental or other factors that might have an effect on the outcome of interest.
This is in [obvious] contrast with the situation among people leading their daily lives. In the context of influenza, it is highly probable that almost everyone, vaccinated or not, who lives in a community during an outbreak of influenza is exposed to the circulating influenza viruses. The consequences of such exposures in vaccinated persons are not known, but it would be difficult to believe that these would not induce any immunological responses. The efficacy of influenza vaccine is far from optimum and, especially among young children, symptomatic
breakthrough illnesses happen frequently despite vaccination. Because influenza vaccination cannot prevent all symptomatic infections, it could be postulated that its ability to prevent asymptomatic infections is even worse [!].
A logical implication of this is that most vaccinated children are repeatedly attacked by wild-type influenza viruses during local outbreaks and might develop asymptomatic infections that, in turn, can induce the development of partial heterosubtypic immunity
On the basis of the accumulating data from the present A H1N1 pandemic, the authors’ concern does not seem warranted. By contrast with regular influenza seasons in which the highest attack rates are seen in young children, 2,3
the 2009 A H1N1 pandemic has so far primarily affected adolescents and young adults. 4 Available data from the USA also suggest that paediatric influenza-associated case mortality during the present pandemic—the first one in the era of a general recommendation to vaccinate all children in the country—seems not to be higher than that seen during the three preceding regular influenza seasons.5
In a case–control study from Mexico, seasonal influenza vaccination was associated with a reduced risk of severe pandemic H1N1 infection.6 Moreover, the well-known W-shaped mortality curve from the infamous 1918 A H1N1 pandemic—during which time no vaccine was available—does not support the authors’ hypothesis. 7 If heterosubtypic immunity induced by repeated influenza infections during childhood provided any substantial protection against severe forms of illness, no such increased mortality among young adults should have been seen.[this is a nice observation I think]
We fully agree that there is a need for more effective influenza vaccines that would induce broader immune responses.
In children, the live-attenuated influenza vaccine seems to be more effective than the conventional inactivated vaccine,8 but the live vaccine is not available in Europe at present, and even in the USA it is only indicated for children 2 years of age or older.9 Public health decisions should be based on the best clinical evidence available. There is ample evidence for the great burden of influenza in young children,2,3,10 and this burden appears during every influenza
season. By contrast, there is no clinical evidence that vaccinating children against influenza would prevent the induction of heterosubtypic immunity and thereby be disadvantageous to children in the long run.
While waiting for improved influenza vaccines, the simple question isshould we let young children suffer from a severe and potentially lethal but easily preventable illness, just because there is a theoretical possibility that withholding vaccination might result in a slightly less severe illness sometime in the future? We believe that the answer to this question is a simple one.”
Did the post assure you, or not!, (you can tell me)
References:
1 Bodewes R, Kreijtz JHCM, Baas C, et al. Vaccination against human influenza A/H3N2 virus prevents the induction of heterosubtypic immunity against lethal infection with avian influenza A/H5N1 virus. PLoS One 2009;4: e5538.
2 Heikkinen T, Silvennoinen H, Peltola V, et al. Burden of infl uenza in children in the community. J Infect Dis 2004; 190: 1369–73.
3 Poehling KA, Edwards KM, Weinberg GA, et al. The underrecognized burden of influenza in young children. N Engl J Med 2006; 355: 31–40.
4 Gilsdorf A, Poggensee G, on behalf of the working group pandemic influenza A(H1N1)v. Infl uenza A(H1N1)v in Germany: the first 10,000 cases. Euro Surveill 2009; 14: pii=19318.
5 CDC. Seasonal infl uenza—weekly report: infl uenza summary update. Atlanta, GA: Centers for Disease Control and Prevention, 2009. http://www.cdc.gov/fl u/weekly/ (accessed Oct 12, 2009).
6 Garcia-Garcia L, Valdespino-Gómez JL, Lazcano-Ponce E, et al. Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009: case-control study in Mexico City. BMJ 2009; published online Oct 6. DOI:10.1136/bmj.b3928.
7 Glezen WP. Emerging infections: pandemic influenza. Epidemiol Rev 1996;18: 64–76.
8 Belshe RB, Edwards KM, Vesikari T, et al. Live attenuated versus inactivated infl uenza vaccine in infants and young children. N Engl J Med 2007;356: 685–96.
9 CDC. Seasonal influenza—recommendations for using TIV and LAIV during the 2009–10 influenza season. Atlanta, GA: Centers for Disease Control and Prevention, 2009. http://www.cdc.gov/flu/professionals/acip/
recommendations.htm (accessed Oct 12, 2009).
10 Heikkinen T, Booy R, Campins M, et al. Should healthy children be vaccinated against infl uenza? Eur J Pediatr 2006; 165: 223–28
Dear readers, Peace be upon you all!
This post comes in reply for what was published recently by, Rogier Bodewes and colleagues (Yearly influenza vaccinations: a double-edged sword?) urging “re-evaluation of vaccine recommendations because the inactivated vaccine available at present does not induce heterosubtypic immunity and might make infants more susceptible to pandemic influenza.”1,
and before reading the reply, it would worth mentioning that heterosubtypic immunity is an immunity that is cross-protective between different influenza A virus subtypes
a reply came recently in the Lancet,
“… Bodewes and colleagues’ concern is primarily on the basis of their recent animal experiment.1, In animal studies, the investigators have full control over any environmental or other factors that might have an effect on the outcome of interest.
This is in [obvious] contrast with the situation among people leading their daily lives. In the context of influenza, it is highly probable that almost everyone, vaccinated or not, who lives in a community during an outbreak of influenza is exposed to the circulating influenza viruses. The consequences of such exposures in vaccinated persons are not known, but it would be difficult to believe that these would not induce any immunological responses. The efficacy of influenza vaccine is far from optimum and, especially among young children, symptomatic
breakthrough illnesses happen frequently despite vaccination. Because influenza vaccination cannot prevent all symptomatic infections, it could be postulated that its ability to prevent asymptomatic infections is even worse [!].
A logical implication of this is that most vaccinated children are repeatedly attacked by wild-type influenza viruses during local outbreaks and might develop asymptomatic infections that, in turn, can induce the development of partial heterosubtypic immunity
On the basis of the accumulating data from the present A H1N1 pandemic, the authors’ concern does not seem warranted. By contrast with regular influenza seasons in which the highest attack rates are seen in young children, 2,3
the 2009 A H1N1 pandemic has so far primarily affected adolescents and young adults. 4 Available data from the USA also suggest that paediatric influenza-associated case mortality during the present pandemic—the first one in the era of a general recommendation to vaccinate all children in the country—seems not to be higher than that seen during the three preceding regular influenza seasons.5
In a case–control study from Mexico, seasonal influenza vaccination was associated with a reduced risk of severe pandemic H1N1 infection.6 Moreover, the well-known W-shaped mortality curve from the infamous 1918 A H1N1 pandemic—during which time no vaccine was available—does not support the authors’ hypothesis. 7 If heterosubtypic immunity induced by repeated influenza infections during childhood provided any substantial protection against severe forms of illness, no such increased mortality among young adults should have been seen.[this is a nice observation I think]
We fully agree that there is a need for more effective influenza vaccines that would induce broader immune responses.
In children, the live-attenuated influenza vaccine seems to be more effective than the conventional inactivated vaccine,8 but the live vaccine is not available in Europe at present, and even in the USA it is only indicated for children 2 years of age or older.9 Public health decisions should be based on the best clinical evidence available. There is ample evidence for the great burden of influenza in young children,2,3,10 and this burden appears during every influenza
season. By contrast, there is no clinical evidence that vaccinating children against influenza would prevent the induction of heterosubtypic immunity and thereby be disadvantageous to children in the long run.
While waiting for improved influenza vaccines, the simple question isshould we let young children suffer from a severe and potentially lethal but easily preventable illness, just because there is a theoretical possibility that withholding vaccination might result in a slightly less severe illness sometime in the future? We believe that the answer to this question is a simple one.”
Did the post assure you, or not!, (you can tell me)
References:
1 Bodewes R, Kreijtz JHCM, Baas C, et al. Vaccination against human influenza A/H3N2 virus prevents the induction of heterosubtypic immunity against lethal infection with avian influenza A/H5N1 virus. PLoS One 2009;4: e5538.
2 Heikkinen T, Silvennoinen H, Peltola V, et al. Burden of infl uenza in children in the community. J Infect Dis 2004; 190: 1369–73.
3 Poehling KA, Edwards KM, Weinberg GA, et al. The underrecognized burden of influenza in young children. N Engl J Med 2006; 355: 31–40.
4 Gilsdorf A, Poggensee G, on behalf of the working group pandemic influenza A(H1N1)v. Infl uenza A(H1N1)v in Germany: the first 10,000 cases. Euro Surveill 2009; 14: pii=19318.
5 CDC. Seasonal infl uenza—weekly report: infl uenza summary update. Atlanta, GA: Centers for Disease Control and Prevention, 2009. http://www.cdc.gov/fl u/weekly/ (accessed Oct 12, 2009).
6 Garcia-Garcia L, Valdespino-Gómez JL, Lazcano-Ponce E, et al. Partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza A/H1N1 2009: case-control study in Mexico City. BMJ 2009; published online Oct 6. DOI:10.1136/bmj.b3928.
7 Glezen WP. Emerging infections: pandemic influenza. Epidemiol Rev 1996;18: 64–76.
8 Belshe RB, Edwards KM, Vesikari T, et al. Live attenuated versus inactivated infl uenza vaccine in infants and young children. N Engl J Med 2007;356: 685–96.
9 CDC. Seasonal influenza—recommendations for using TIV and LAIV during the 2009–10 influenza season. Atlanta, GA: Centers for Disease Control and Prevention, 2009. http://www.cdc.gov/flu/professionals/acip/
recommendations.htm (accessed Oct 12, 2009).
10 Heikkinen T, Booy R, Campins M, et al. Should healthy children be vaccinated against infl uenza? Eur J Pediatr 2006; 165: 223–28
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