Influenza Vaccine During Pregnancy - Research Paper Example

? "Influenza Vaccine during Pregnancy" Influenza or flu is extremely infectious viral illness, caused by RNA virus. Influenza involves myalgia affecting back muscles and onset of abrupt high fever. Children suffering with influenza may have pneumonia as complication of the condition, Reye syndrome is also found to be associated with the children with influenza B. The condition is devastating as it may result in serious complication encompassing vomiting, confusion and coma, myocarditis etc. Considering the disease to be of high significance, vaccines are provided during pregnancy as a preventive measure. The prevalence of vaccine occurred with the appearance of H1N1 pandemic (pH1N1) influenza. As a result of this, pregnant women are provided with monovalent H1N1 vaccine, irrespective of preceding influenza infection, in order to provide the fetus with the passive immunity. However, this precautionary step is found to influence fetal development and growth resulting in reduced gestational age and augmentation in birth weight (Stinhoff et al, 2012). Although recommended, there is no encouraging evidence that influenza vaccine is effective during pregnancy. Moreover, there is no evidence to assess the risk of vaccination provided to protect influenza during pregnancy. Thimerosal, mercury containing preservative which is present in most inactivated influenza vaccination is found to influence appropriate neural development and may result in autism or teratogenic anomalies, mutagenicity and even fetal death. Introduction Influenza vaccine lays the basis to reduce the health encumber due to influenza. Inactivated viral matter, administered through intramuscular injection, has been in use as a vaccine since 1940s. Such vaccines were given to one who is either of six months or older. Later, in 1960s, LAIV (Live Attenuated, cold-adapted influenza vaccines) were developed, administered through nasal spray, licensed in US in 2003. These vaccines do not contain adjuvants. LAIV is used for medicating non-pregnant individuals belonging to the age of 2-49 years. Influenza vaccine as other vaccines induces the formation of antibodies against major surface glycoproteins hemaglutinin and neuraminidase. The immune response gains its peak at 2-4 weeks after the first dose, whereas previously unvaccinated children below 9 years were recommended with two doses of vaccine, the priming dose as well as the booster dose. The adverse reaction observed in these individuals involves soreness, fever, malaise and Guillian- Barre Syndrome (GBS) (1/100,000) recipients, other adverse drug reports encompass nasal congestion, headache, myalgias or fever (Stinhoff et al, 2012). Pregnancy is a condition that affects immune system to a greater extent as a result woman becomes prone to the health hazards caused by the flu or other complicated condition such as pneumonia or respiratory distress. Further, these conditions may culminate into premature labor or delivery of a preterm baby. Prevention of flu is therefore highly imperative. Vaccination as a preventive measure is a way to protect the fetus, infant stage. Childhood flu vaccines can be provided at or after 6 months of age. However, vaccination during the pregnancy results in the formation of antibodies which are passed on to the developing fetus and hence a passive protection or immunity is provided to the fetus. This flu vaccine is prepared from the inactivated virus while the nasal spray is prepared from the live virus which is contraindicated during pregnancy (Ayoub & Yazbak, 2006). Symptoms of Influenza Symptoms of influenza involve fever, myalgia, malaise, headache, fatigue, cough, sore throat, rhinitis etc. Such conditions could be assessed by performing viral culture and testing for the presence of viral antigen. Influenza virus possesses airborne transmission and person to person contact. The virus possesses an incubation period of two days and there is an abrupt onset of these symptoms. Observations reveal that influenza is accompanied by the complications like pneumonia, bronchitis or sinusitis and under rare condition encephalitis or transverse myelitis or Reye syndrome, pericarditis. More than 90% fatalities occur among the elderly population (Prevention and Control of Influenza, 2004). Pathophysiology of Influenza Influenza virus is encapsulated, possesses single stranded (ss) RNA comprising 8 genes, belong to the viral family Orthomyxoviridae. The three kinds of influenza virus encompass A, B, C. Of these strains A is the most prevalent form of virus that is capable of causing infection to humans. Viral coat of A type possess 10 proteins while the viral matter of type B has 11 proteins. Most of the virus has hemagglutinin and neuraminidase which play vital role in the viral virulence and aims at targeting or neutralizing antibodies. The major role played by the hemagglutinin involves binding with respiratory epithelial cells that permits the cellular infection on the other hand neuraminidase cleaves the bond which is responsible for holding the newly formed viral particles as a result of viral replication inside the cell to promote viral multiplication (Gubareva, 2000). Influenza in Pregnancy According to Irwing et al (2000), maternal and neonatal results were compared for the cases where woman witnessing infection with influenza virus during second and third trimester with their control counterparts. According to the study reported by Ayoub & Yazbak, (2006), 11% pregnant cases had serological evidence of illness but detectable influenza specific IgM was not found, moreover, influenza virus cannot have transplacental transmission or induction of autoantibody formation is not reported in influenza- complicated pregnancies. Influenza does not influence labour, or health of the newborn; it does not influence maternal health (Irwing et al, 2000). Efficacy of Influenza vaccine: How safe is influenza vaccine According to ACIP, there is a thin demarcation to highlight the fact that influenza vaccine can potentially influence pregnancy. Reports highlighted by Ayoub & Yazbak, (2006), “Researchers estimate that an average of one to two hospitalizations can be prevented for every 1,000 pregnant women vaccinated..” Moreover the study also highlighted the fact in terms of statistics, no significant difference was found between vaccinated and non-vaccinated women. Vaccination was found to display no impact on the rate of illness in women who suffers with asthma. According to National Toxicology Program (NTP), thimerosal present in the inactivated vaccine acts as a poison, it is also considered as a proven carcinogen and teratogen. It is potentially capable of bringing mental retardation, lack of co-ordination in speech children, loss of coordination in speech, irritability etc. (Trasande, 2005). Thimerosal weakens fertility and impairs the ciliary movement of the trachea in sheep and therefore it is presumed to impair reproductive capacity in females and reduce sperm motility in men. Highlighting the fact that if a pregnant woman could manage to make her fetus survive then as a child is liable to have infertility (Dally, 1997). These studies highlight the fact that the influenza vaccine impose a great deal of toxicity which affects various organs of the fetal vaccination survivors. In the study carried out by the Steinhoff et al,(2012), it has been confirmed that influenza immunization during pregnancy affects the birth weight as well as the gestational age, while the prevention against the seasonal influenza in pregnancy, through immunization influences fetal growth while the pandemic strains affects the fetus to a greater extent. However, it was also reported that maternal response to the influenza virus affects maternal metabolism as well as placental function and also implicates nutrition transfer process through placenta. During the process maternal chemokines, cytokines and other factors also cross the placenta and affects the metabolism of fetus (Brydon, 2005). However, recent studies report that there is a marked reduction in the birth weight has been observed in United States, United Kingdom and other parts of North America. On the other hand vaccination is imperative to prevent fetus developing inside a pregnant in first few months. It is observed that tetanus could be conquered by means of immunization of pregnancy woman, similar strategy could also be followed for the influenza vaccination to make it a success. According to Zaman et al, (2008), inactivated influenza vaccination could bring 63% of laboratory proven infection in infants while a decline is observed to 36% in respiratory illness. Reports highlight the fact that there is a decline in the incidence of influenza cases and hospitalization of infants after influenza vaccination. This could be made possible due to passive immunization that is given to the infant by the mother through placenta. Conclusion Influenza spreads potentially in the community and is capable of causing spread and intensity in illness of the patient. The virus is capable of changing its antigenic forms from 1918 to 2009. Human is the indirect host and is known that pig serves as a host for human as well as avian species. Its transmission is through droplet nuclei as well as body discharges. The virus invades the respiratory epithelium after the incubation duration of 1-7 days. A damage to epithelium us followed by immune response. Characters displayed by the patients encompass fever, cough, sore throat, diarrhoea, vomiting followed by hospitalization. Vaccination against the devastating disease influenza is highly essential to prevent the development of complications especially pneumonia in children. During pregnancy the immunity provided to the developing fetus is passive, it can prevent the fetus from influenza. Reports of teratogenic as well as carcinogenic implications of the condition have been observed. Although with research studies the success rate has augmented but still a lot of controversies regarding the influenza vaccine are gaining prevalence. On one hand the reports highlight the positive consequences of the influenza vaccine in preventing the disease condition while on the other hand there are reported incidence to display the teratogenic as well as carcinogenic impact of the influenza vaccine. Dreaded diseases like pH1N1 could be combated due to the administration of pH1N1 vaccination. Vaccination to pregnant women provides passive immunity and with the advances in molecular biology and technology greater protection could be procured. References Ayoub, D. M., Yazbak, F. E. (2006). Influenza Vaccination During Pregnancy: A Critical Assessment of the Recommendations of the Advisory Committee on Immunization Practices (ACIP). (2006). Journal of American Physicians and Surgeons, 11(2), 41- 47. Brydon, E.W., Morris, S.J., Sweet, C. (2005). Role of apoptosis and cytokines in influenza virus morbidity. FEMS Microbiol Rev, 29, 837–50. Dally, A. (1997). The rise and fall of pink disease. Soc Hist Med, 10, 291-304. Fiore, A. E., Bridges, C. B., Cox, N. J. (2009). Seasonal Influenza vaccines. Curr Top Microbiol Immunol, 333, 43-82. Gubareva, L.V., Kaiser, L., Hayden, F.G. (2000). Influenza virus neuraminidase inhibitors. Lancet, 355(9206), 827-35. Irving WL, James DK, Stephenson T, et al. (2000). Influenza virus infection in the second and third trimesters of pregnancy: a clinical and seroepidemiological study. Br J Obstet Gynaecol 107, 1282- 1289. Prevention and Control of Influenza. Recommendations of the Advisory Committee on Immunization Practices (ACIP). (2004), 53(May 28, RR6), 1-44. Steinhoff, M. C., Omer, S. B., Roy, E., Arifeen, S. E., Raquib, R., Dobb, C., Breiman, R. F., Zaman, K. (2012). Neonatal outcomes after influenza immunization during pregnancy: a randomized controlled trial. CMAJ, 184(6), 645-653. Trasande, L., Landrigan, P.J., Schechter, C. (2005). Public health and economic consequences of methylmercury toxicity to the developing brain. Environ Health Perspect, 113, 590-596. Zaman, K., Roy, E., Arifeen, S. A., Rahman, M., Raquib, R., Wilson, E., Omer, S. B., Shahid, N. S., Breiman, R. F., Steinhoff, M. C. (2008). Effectiveness of Maternal Influenza Immunization in Mothers and Infants. N Engl J Med, 359, 1555-1564. Read More