Archive

Archive for the ‘The Vaccines’ Category

Flu vaccine safe to administer to those with egg allergies

October 20, 2010 1 comment

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

Advertisements

Everything you ought to know about the flu

October 20, 2010 2 comments

Well, not exactly everything, but a lot.

What is “the flu”?

Influenza, or “the flu” is an extremely contagious respiratory illness caused by influenza A or B viruses. Flu appears most frequently in winter and early spring. The flu virus attacks the body by spreading through the upper and/or lower respiratory tract. There are 3 types of flu viruses, A, B and C which can cause the flu, and new strains (especially the A type) evolve every few years.

Type A viruses are responsible for major flu epidemics every few years. Type B is less common and generally results in milder cases of flu. However, major flu epidemics can occur with type B every three to five years. There is a third type of virus, C, which also can infect but does not produce flu symptoms.

What are the symptoms/effects of the flu?

Besides generally making one feel miserable, here is a list of some of the most typical flu symptoms/effects.

  • Headaches
  • Severe aches and pains in the joints and muscles and around the eyes
  • Cough
  • Respiratory congestion
  • Fever
  • Chills
  • Fatigue & exhaustion
  • Severe flu can lead to pneumonia
  • Sore throat and watery discharge from your nose

Are there any complications that can arise from the flu?

The most common flu complications include viral or bacterial pneumonia, muscle inflammation, and infections of the central nervous system or the sac around the heart. Other flu complications may include ear infections, sinus infections, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes.

Those at highest risk for flu complications include adults over 50, children ages 6 months to 4 years, nursing home residents, adults and children with heart or lung disease, people with compromised immune systems (including people with HIV/AIDS), and pregnant women.

How does flu spread?

The flu is spread from person to person through respiratory secretions and typically sweeps through large groups of people who spend time in close contact, such as in daycare facilities, school classrooms, college dormitories, military barracks, offices, and nursing homes.

Flu is spread when a person inhales droplets in the air that contain the flu virus, make direct contact with respiratory secretions through sharing drinks or utensils, or handle items contaminated by an infected person. In the latter case, the flu virus on your skin infects you when you touch or rub your eyes, nose, or mouth. That’s why frequent and thorough hand washing is a key way to limit the spread of influenza. Flu symptoms start to develop from one to four days after infection with the virus.

Will one catch the flu if one goes out in the cold or gets wet by cold rain?

No. The flu is a viral infection; you need to come in contact with the flu virus to get infected. Feeling cold or being wet does not give you the flu. It might give you a runny nose though and other symptoms that may be reminiscent of the flu, but it does not cause a flu infection.

What are the symptoms/effects of the flu vaccine?

The most common side effects of the flu vaccine (both inactivated and LAIV) include mild:

  • Swelling at the site of the injection (inactivated only)
  • Headache
  • Cough
  • Body ache
  • Fever

When should one get the flu vaccine?

As soon as it is available.

How many types of flu vaccines are there?

There are two types of flu vaccine. Inactivated and LAIV. The inactivated vaccine is given as a shot, generally in the arm, while the LAIV version is a nasal spray. The main difference between the two is that the inactivated, or the shot, contains dead viruses, whereas the LAIV version contains alive, but extremely weakened, viruses. Because of that, the spray is expected to be more effective in inducing an immune reaction than the shot.

Why is the flu vaccine different every year?

Two of the three flu viruses are responsible for causing flu, type A and type B. Type A has 16 subtypes, while Type B is not categorized by subtypes.  They both can mutate, especially type A which results in new strains every few years. Every given year, any combination of various strains of the various subtypes of A and of Type B can be in circulation and causing flu.

Every given year, both the LAIV and Inactivated vaccine contain three strains of influenza virus that are chosen each year based on what scientists predict will be the circulating viruses for the flu season. Given the long production times, it is impossible to know for sure which strains will be prevalent in the upcoming season, so every year scientists have to do their best to predict what they think will be the prevalent strains. Usually this process is done months ahead of the actual flu season. This is why the flu vaccine is different each year, and why we have to get re-vaccinated each year.

Which strains does the 2010 vaccine protect against?

Every year, the flu vaccine, protects against 3 specific strains of viruses that cause flu. The 2010 vaccine protects against two A viruses and one B virus. This year the vaccine protects against these 3 strains:

  • an A/California/7/2009 (H1N1)–like virus (Swine Flu)
  • an A/Perth/16/2009 (H3N2)–like virus
  • and a B/Brisbane/60/2008–like virus

Can you get the flu from the flu vaccine?

No! You cannot get the flu from the flu vaccine. You may, however, experience some flu-like symptoms, which can be experienced from any vaccine in some cases and doesn’t have anything to do with the actual disease you’re being inoculated against.

How effective is the flu vaccine?

The effectiveness of the flu vaccine depends on the strains in circulation and the strains the vaccine prevents from. When the vaccine viruses and circulating viruses are well-matched, the vaccine can reduce the chances of getting the flu by 70% to 90% in healthy adults.

Can you get the flu, even if you get vaccinated?

Yes. Firstly, as we already saw, the 3 strains in the flu vaccine have to be guessed in advance of the flu season. If there is a good match between the predicted strains and the actual strains in circulation, the vaccine will provide good protection. On the other hand, even if there is a perfect match, no vaccine is 100% effective, so even then a person who got vaccinated may still develop the flu. However, in general, people who are vaccinated experience milder symptoms than the non-vaccinated ones.

Who should get the flu vaccine?

Except for high risk groups that are advised to skip the vaccine, it is recommended that everyone over 6 months of age should get the flu vaccine.

Who should not get the flu vaccine?

Anyone with a severe allergy to eggs or egg products should not get a flu shot. Other people who should not get a flu shot include:

  • Infants under 6 months old.
  • Anyone who has had a severe reaction to a past flu shot or nasal spray.
  • Someone with Guillain-Barre syndrome.
  • People with moderate to severe illness with a fever; they should be vaccinated after they have recovered.

How Long Am I Contagious After I Get the Flu?

You are contagious for up to seven days after the onset of the flu, although the flu virus can be detected in secretions up to 24 hours before the onset of symptoms. This means you might transmit the flu virus a full day before your flu symptoms begin.

In young children, the flu virus can still be spread in the secretions even into the second week of illness.

How Can I Prevent the Flu?

To prevent the flu, be sure to keep your hands clean — making sure to wash them frequently to remove germs — and get a flu shot. The CDC develops a flu vaccine based on the type A strain that they believe will be most prevalent in the coming flu season. This is the vaccine you get with the annual flu shot or FluMist nasal spray.

Give me some statistics please?

-Every year during flu season, 1 in 20 Americans will contract the disease. Some years incidence can be as high as 1/5.

-Annually there are about 200,000 hospitalizations and an average of 23,600 annual deaths from the flu  in the US alone.


Sources

WebMD

Flu.gov

CDC Flu Website

World Health Organization Influenza Page

Safety of influenza vaccine during pregnancy

October 7, 2010 Leave a comment

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.

Safety of influenza vaccination during pregnancy.

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.

Maternal Flu Vaccination and Effect on Flu Infection in Young Infants

October 6, 2010 2 comments

A new study, published online at the Archives of Pediatrics & Adolescent Medicine, looks at the effects of mom’s flu vaccine on young infants.

Maternal Influenza Vaccination and Effect on Influenza Virus Infection in Young Infants

Angelia A. Eick, PhD; Timothy M. Uyeki, MD, MPH, MPP; Alexander Klimov, PhD; Henrietta Hall, MS; Raymond Reid, MD; Mathuram Santosham, MD; Katherine L. O’Brien, MD, MPH

Arch Pediatr Adolesc Med. Published online October 4, 2010. doi:10.1001/archpediatrics.2010.192

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.

3-dose 7-Valent pneumococcal vaccine use associated with increased nasopharyngeal acquisition of pneumococcal Serotype 19A Strain

October 5, 2010 Leave a comment

A recent study published in the Journal of the American Medical Association (JAMA) has found an association between the 7-valent pneumococcal vaccine (PCV-7) and an increase in nasopharyngeal (in the nose and throat) acquisition of pneumococcal serotype 19A strain, which is not one of the 7 strains the PCV-7 protects from. According to the authors of the study, a possible association had been observed between the use of PCV-7 vaccine and a rapid increase in serotype 19A strain acquisition, but studies had never been done to confirm this association, and the current study is the first one to address that concern. Let us look at it:

Pneumococcal Conjugate Vaccination and Nasopharyngeal Acquisition of Pneumococcal Serotype 19A Strains

Elske J. M. van Gils, MD; Reinier H. Veenhoven, MD, PhD; Eelko Hak, PhD; Gerwin D. Rodenburg, MD; Wendy C. M. Keijzers; Debby Bogaert, MD, PhD; Krzysztof Trzcinski, DVM, PhD; Jacob P. Bruin; Loek van Alphen, PhD; Arie van der Ende, PhD; Elisabeth A. M. Sanders, MD, PhD

JAMA. 2010;304(10):1099-1106. doi:10.1001/jama.2010.1290

Study Summary – The study was conducted in the Netherlands. 948  healthy infants, from 6 weeks up to 24 months of age, were enrolled, and followed between July 7, 2005, and February 14, 2008. Infants were randomly assigned to receive 2 doses of PCV-7 at 2 and 4 months; 2 + 1 doses of PCV-7 at 2, 4, and 11 months; or no dosage (unvaccinated control group). Nasopharyngeal swabs were obtained at the age of 6 weeks and at 6, 12, 18, and 24 months to test for the presence of the 19A strain of the pneumococcal bacteria. Rates of bacterial presence were compared between the different groups.

Results – 54 nasopharyngeal serotype 19A carriage isolates from 318 in the 2-dose group, 66 isolates from 327 in the 2 + 1-dose group, and 33 isolates from 303 in the unvaccinated were collected from 6 weeks through 24 months. The cumulative proportion who tested positive for new nasopharyngeal serotype 19A acquisition from 6 through 24 months of age was significantly higher in those having received the 2 + 1-dose PCV-7 schedule (16.2%; 95% confidence interval [CI], 12.6%-20.6%) vs those who were unvaccinated (9.2%; 95% CI, 6.5%-13.0%; relative risk [RR], 1.75; 95% CI, 1.14-2.70) but not after a 2-dose schedule (13.2%; 95% CI, 9.9%-17.4%; RR, 1.43; 95% CI, 0.91-2.25).

Conclusion – This study is methodologically sound. The sample size was fairly large, subjects were randomly assigned, and there was a proper control group. If the results of this study hold, and can be replicated, it would strongly suggest that a 3-dose of the PCV-7 pneumococcal vaccine might lead to higher rates of acquisition of the 19A strain in infants between 6 weeks and 24 months of age. It is very interesting that there were no statistically significant differences between the non-vaccinated children and the ones that had not received the 3rd dose yet. From the information that can be gleamed by the abstract of the study, the authors don’t seem to speculate on why it appears that the 3rd dose makes the difference. They conclude simply as such:

A 2 + 1-dose PCV-7 schedule was associated with an increase in serotype 19A nasopharyngeal acquisition compared with unvaccinated controls.

How should we interpret this study? By the author’s own admission, this is the first study to look at the association between PCV-7 and increased serotype 19A acquisition rates. As such, it is imperative that its results be replicated, to rule out mistakes, or other things that could have affected the results. On the other hand, the study looks to have been conducted well, and appears to have been designed properly. It provides intriguing evidence that 3 doses of the PCV-7 vaccine might be causally related to an increase in nasopharyngeal acquisition of pneumococcal serotype 19A Strain. More studies are needed to verify these results.

Until then, the best course of action is to speak to your pediatrician, and talk to her about using the 13, or the 23, valent version of the pneumococcal vaccine which also covers serotype 19A strains of the pneumococcal bacteria. You should not unilaterally decide to skip the pneumococcal vaccination completely based solely on this one study.

Categories: Pneumococcal, Safety

Reduction in Gastroenteritis With the Use of Pentavalent Rotavirus Vaccine in a Primary Practice

October 2, 2010 1 comment

I have previously looked at studies that looked at acute gastroenteritis (AGE) rates of hospitalizations before and after the introduction of the pentavalent rotavirus vaccine (RV5). Those studies noted a significant reduction in AGE hospitalization rates following the introduction of the RV5 in 2006. In this entry, I will summarize yet another study along the same lines.

AGE, commonly referred to as the “stomach flu“,  is a viral infection, and rotavirus is the leading cause of severe gastroenteritis in children, credited with causing about 50% of acute gastroenteritis hospitalizations during January-June among U.S. children. Logically, if rotavirus causes it, and if an effective vaccine is introduced, we ought to observe statistically significant decreases in gastroenteritis hospitalization rates, and this is what this analysis was set up to do.

The study we will look at today, was published in the journal Pediatrics and the abstract can be accessed by clicking the link below.

Reduction in Gastroenteritis With the Use of Pentavalent Rotavirus Vaccine in a Primary Practice

Rodolfo E. Bégué, MDa, Keith Perrin, MDb

Study SummaryThe authors followed up children under 5 years of age, who presented with AGE in a large pediatrics practice in New Orleans, between 2004 and 2009. Primary care physician office visits, emergency department visits, and hospital admissions were identified by review of records. RV testing was performed only on those who were seen at the hospital. Overall, about 16,000 children were included in this study.

Results – For 2006–2007, 2007–2008, and 2008–2009, 11.1%, 40.3%, and 45.6% of age-eligible children, respectively, received 1 dose of RV5.  As compared with 2004–2005 (before RV5), in 2007–2009, there was a significant decrease in all-cause AGE office visits (23%) and hospitalizations (50%). RV-positive cases (emergency department visits or hospitalizations) decreased by 67%. The decrease in RV-positive cases was more evident among children who were younger than 2 years (81%), with a strong trend among those who were aged 2 to <5 years (41%).

Conclusion – This study adds more evidence that the introduction of the pentavalent rotavirus vaccine led to a significant decrease in all-cause AGE hospitalizations, and especially rotavirus-caused AGE. Taken together with the previous 3 studies we’ve reviewed, the evidence seems very solid and is strongly suggestive of a correlation between the introduction of RV5 in 2006, and significant decreases in AGE hospitalizations. The authors of the above study concluded as such:

Increased use of RV5 in a pediatric practice was associated with fewer AGE office visits and hospitalizations. The reduction was specific for RV-positive AGE and seen among children who were targeted for immunization as well as older groups, suggesting a herd-immunity effect.

Vaccine Has Cut Child Cases of Bacterial Pneumonia, Says Study

September 29, 2010 1 comment

READ THE FULL ARTICLE AT SCIENCE DAILY

The number of children admitted to English hospitals with bacterial pneumonia decreased by a fifth in the two years following the introduction of a vaccine to combat the disease, according to a new study published in the journal Thorax.

Bacterial pneumonia is a serious illness caused by Streptococcus pneumoniae bacteria that mostly affects babies, young children and elderly people. In Europe, around one in ten deaths in the under-fives is caused by the disease.

Bacterial pneumonia usually develops as a complication following a respiratory tract infection such as influenza. Symptoms include difficulty breathing, wheezing, fever and loss of appetite.

In September 2006, a vaccine known as PCV7 was introduced into the childhood primary immunisation programme across the UK, to protect against seven different strains of Streptococcus pneumoniae bacteria.

Today’s study, led by researchers from Imperial College London, shows that in the first two years following the introduction of this vaccine, hospital admissions for bacterial pneumonia decreased by 19 per cent amongst children aged under 15 years. Admissions for empyema, a rare and serious complication of bacterial pneumonia, decreased by 22 per cent.

The pneumococcal vaccine is administered at two, three and 13 months of age. When it was first introduced there was a catch-up campaign for children up to two years. Take-up of the vaccine over the study period was high. It was administered to an average of 84 per cent of eligible children in England in the first year following its introduction and 91 per cent the following year.

Categories: News, Pneumococcal