New guidelines by the American Academy of Allergy Asthma & Immunology say that individuals with egg allergies can safely receive the flu vaccine, without a skin test being performed first. Flu vaccines are grown in chicken eggs, which raised concerns about possible allergic reactions to residual egg protein. Up to now, precautionary steps were taken, which included vaccine skin testing, administration via a 2-step graded dose challenging (10%, followed by 90% of the age appropriate dose after a brief observation period), or stepwise desensitization.
This latest AAAAI paper “offers guidance in how to evaluate and treat the patient with egg allergy who desires influenza vaccination, and outlines the latest evidence based approaches to successfully administer the vaccine.” According to the position paper:
Conclusion There has been tremendous growth over the past year in demonstrating that TIV (and H1N1) are safe for egg allergic individuals to receive. While a few concepts bear further study, such as the safety of these vaccines in individuals with severe allergy to egg, it appears that most egg allergic patients can safely receive influenza vaccination if desired. While no particular approach to administering the vaccine has been shown to be the safest and most effective, several methods for providing this service exist. Providers should no longer withhold the vaccine on account of a patient’s egg allergy, and should feel comfortable selecting one of two strategies we outline for administering the influenza
Today we will look at the recent recommendation by the CDC, the American College of Obstetricians and Gynecologists, that, all people over 6 months of age, including pregnant women receive the flu vaccine. Anti-vaccination groups have already come out, insinuating that the safety of the flu vaccine given during a woman’s pregnancy has not been established. Is that true? Are there any studies that have looked at the safety of the influenza vaccine for pregnant women? The answer is yes, at the very least there is one that I was able to find, using simply Google.
Munoz FM, Greisinger AJ, Wehmanen OA, Mouzoon ME, Hoyle JC, Smith FA, Glezen WP.
Study Summary – The objective of the study was to “evaluate the safety of influenza vaccine that is administered in the second or third trimester of gestation”. A retrospective electronic database search of 5 influenza seasons (July 1, 1998, to June 30, 2003) was performed at a large multispecialty clinic in Houston, Texas. Immunization rates were calculated, and outcomes of pregnancy were compared between healthy women who received influenza vaccine, and a control group of healthy unvaccinated women who were matched by age, month of delivery, and type of medical insurance.
Results – Among 7183 eligible mother-infant pairs, only 252 pregnant women (3.5%) received the influenza vaccine. The mean gestational age at the time of influenza vaccination was 26.1 weeks (range, 14-39 weeks). No serious adverse events occurred within 42 days of vaccination, and there was no difference between the groups in the outcomes of pregnancy (including cesarean delivery and premature delivery) and infant medical conditions from birth to 6 months of age.
Conclusion – This study provides good evidence that pregnant women who receive the flu vaccine during the last 2 trimesters of the pregnancy, and their babies at least up to 6 months of age, face no more risks or complications than pregnant women who do not receive the flu shot during the last 2 trimesters of their pregnancy, and their babies up to 6 months of age. It appears the claims of the anti-vaccination crowd are rejected, at least as far as this study is concerned. The authors concluded as such:
Influenza vaccine that was administered in the second or third trimester of gestation was safe in this study population.
A new study, published online at the Archives of Pediatrics & Adolescent Medicine, looks at the effects of mom’s flu vaccine on young infants.
Study Summary – The objective of this study was to assess the effect of seasonal influenza vaccination during pregnancy on laboratory-confirmed flu infections in infants up to 6 months of age. A total of 1160 mother-infant pairs were included in the study. The women gave birth during the regular flu season. Some of them received the flu vaccine, some didn’t. The assignment to either receive the flu vaccine or not was not random. The study authors looked at actual lab-confirmed influenza illnesses (ILI), and ILI hospitalization rates of the infants as the main outcomes. They compared ILI confirmed rates, and ILI hospitalization rates between the infants born to vaccinated mother and infants born to unvaccinated mothers.
Results – Infants born to vaccinated mothers were less likely than infants born to unvaccinated mothers to contract ILI. Specifically:
- 41% reduction in the risk of laboratory-confirmed influenza virus infection (relative risk, 0.59; 95% confidence interval, 0.37-0.93)
- 39% reduction in the risk of ILI hospitalization (relative risk, 0.61; 95% confidence interval, 0.45-0.84)
- Significantly higher hemagglutinin inhibition antibody levels at birth and at 2 to 3 months of age
Conclusion – Methodologically, the main design issue is that test subjects were not assigned randomly to either the vaccine or no-vaccine. Furthermore, it appears from the abstract at least, that the mothers in the no-vaccine group did nor receive a placebo shot. The implication is that they simply did not receive a shot and were aware of it, which would affect the blinding as well.
When taken together these two facts should lower our reliance on the results, although not negate it entirely. The differences of 41% and 39% are too big to be due simply to bias introduced by these design issues. So the conclusion should be that given the large sample size and the large differences between the two groups, this study is highly indicative that babies born to vaccinated mothers do receive a tangible benefit from the vaccine, but the actual reduction in infection and hospitalization rates may be a little less than the numbers reported in this study. These conclusions should be compared to other studies, hopefully studies that had better blinding and randomization.
The author’s own conclusion is as such;
Maternal influenza vaccination was significantly associated with reduced risk of influenza virus infection and hospitalization for an ILI up to 6 months of age and increased influenza antibody titers in infants through 2 to 3 months of age.
Today we will look at a study about the efficacy and safety of the flu vaccine in infants. The study was published in The Pediatric Infectious Disease Journal in February 2010.
Englund JA, Walter E, Black S, Blatter M, Nyberg J, Ruben FL, Decker MD; GRC28 Study Team.
Study Summary- This was a double-blind, randomized, placebo-controlled trial, conducted in 1375 healthy US infants 6 to 12 weeks of age. Subjects received 2 doses of trivalent inactivated influenza vaccine (TIV, Fluzone, Sanofi Pasteur; N = 915) or placebo (N = 460) 1 month apart in combination with indicated concomitant vaccines. Solicited adverse events were collected for 7 days following vaccination, and unsolicited adverse events for 28 days. Antibodies to all 3 vaccine strains were measured following the second TIV/placebo dose.
Results – No significant differences were seen between TIV and placebo groups for any safety outcome. Fever > or =38 degrees C within 3 days of vaccination was seen in 11.2% versus 11.7% of TIV versus placebo recipients. Serious adverse events within 28 days were reported in 1.9% of TIV and 1.5% of placebo recipients. Antibody responses to childhood vaccines were similar in both groups. Increased influenza-specific antibody responses in TIV recipients compared with placebo recipients were seen against all 3 strains in TIV recipients, with better responses to influenza A strains noted. Reciprocal geometrical mean titer to H1N1, H3N2, and B were 33, 95, and 11 in TIV recipients versus 7, 9, and 5 for placebo recipients.
Conclusion – This study fulfills all the basic requirements for a well designed scientific study. The sample was large (1,375 participants); it was double-blind, randomized and placebo controlled. This study showed that the trivalent, inactivated flu vaccine was just as safe as the placebo and highly more efficient than placebo in inducing antibody response to all three strains of the virus. The authors concluded as such:
TIV administered to young infants beginning at 6 to 12 weeks of age is safe and immunogenic.
The Advisory Committee on Immunization Practices, an advisory to the Centers for Disease Control and Prevention, is recommending that the Australian flu vaccine Fluvax (double-check the brand name, CSL also makes Afluria and it is not clear which one the ACIP is referring to, based on the article reporting the original problem with the vaccine, it appears to be Fluvax) produced by CSL Biotherapies, which was associated with highly increased instances of convulsions and fever in kids who got the shot in Australia and New Zealand, should not be used by US doctors unless no other brands of flu vaccine are available, and only with children aged 5 or higher. This is a precautionary measure, since investigations on the Australian phenomenon have not been able to explain what in the vaccine could cause these higher rates of side effects.
Committee members were concerned about the unexplained higher rate of fevers and related seizures seen in young children who got the vaccine earlier this year in Australia and New Zealand. In kids under 5, the rates were roughly 10 times that of other flu vaccines. No deaths have been linked to the problem.
This news shows that the government bodies are keeping a close eye on, and are opting for the safe approach with vaccines, contrary to what certain sources of information claim. It is important to keep in mind that the cautionary approach applies only to one specific brand of flu vaccine, not to flu vaccines in general. There is no indication that the other brands pose risks higher than any other year. You should still vaccinate your children for flu, however make a note to ask your doctor which vaccine she’ll be using, to ensure that your child, if under 5 years of age, does not receive the Australian brand, which has been linked to increased rates of seizures and fevers.
Update 08/12/10 – I have been able to verify that the vaccine this recommendation applies to is AFLURIA. For more details please read the official Centers for Disease Control update on the matter.