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<2009 H1N1 Influenza -- Just the Facts: Vaccine Essentials>
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Issue No. 003/09 |
20
November2009
|
Main Topic:
H1N1 FLU
(SWINEFLU)
VACCINE
SAFETY
From Medscape
Infectious Diseases
2009
H1N1 Influenza -- Just the Facts: Vaccine Essentials
John G. Bartlett,
MD
Authors and Disclosures
Published: 09/25/2009; Updated: 10/15/2009
| Editor's Note: This article will be updated frequently, so check
back often for new information. On September 30, 2009, updates were
added on vaccine supply and vaccine response in children. On October
14, 2009, updates were added on FDA vaccine approval and supply; vaccine
types, priorities, dosing, contraindications, and side effects; vaccine
interaction and comparative effectiveness; mandates for healthcare
workers; influenza vaccine coverage in the United States; and findings
of a survey about the public's intent to be vaccinated. |
Update on Influenza A (H1N1)
2009 Monovalent Vaccines
The FDA has approved 4 vaccine
preparations. The following data highlight relevant issues:
- All influenza vaccine preparations
in the United States for the 2009-2010 season contain residual egg protein
and none contain adjuvant;
- Children 6 months to 9
years of age who are given influenza A (H1N1) monovalent vaccine should
receive 2 doses separated by about 4 weeks; persons ? 10 years of age
should receive 1 dose;
- The influenza A (H1N1)
monovalent vaccines were made according to standards used for seasonal
and influenza vaccines and have the same age group indications, precautions,
and contraindications as vaccines that are FDA-approved for seasonal
flu; preliminary data indicate that the safety and efficacy of the 2009
Influenza A (H1N1) monoclonal vaccine is the same as for seasonal flu
vaccines;
- Side effects, including
local pain at the injection site, were reported in 46% of recipients,
and systemic reactions (headache, malaise or myalgias) were reported
in 45%; the safety profile is consistent with the experience with seasonal
flu vaccine;
- Influenza activity due
to influenza A (H1N1) increased in September 2009 and is expected to
continue through fall and winter;
- There is minimal evidence
of significant antigenic change since the first characterization of
the virus in April 2009, indicating that the virus continues to be well
matched with the vaccine strain; and
- The vaccines of the 4 suppliers
have some differences that are important to recognize:
Table 1.
FDA-Approved Influenza A (H1N1) Vaccines
|
Supplier
|
Vaccine Form
|
Mercury µg/0.5 mL
|
Age
|
| MedImmune (nasal spray) |
Live virus 0.2 mL (nasal spray sprayer)
|
0
|
2-49 yrsb
|
| |
|
|
|
| Sanofi (IM)a |
Inactivated
0.25 mL prefilled syringe 0.5 mL prefilled syringe 5 mL multidose
vial
|
0
0
25
|
6-35 mosb
> 36 mosb
> 6 mosb
|
| |
|
|
|
| Novartis (IM)a |
5 mL multidose vial
0.5 mL prefilled syringe
|
25
< 1.0
|
>_ 4 yrsb
> 4 yrsb
|
| |
|
|
|
| CSL Biotherapies, Inc (IM)a |
0.5 mL prefilled syringe 5.0 mL multidose vial
|
0
24.5
|
> 18 yrs
> 18 yrs
|
| |
|
|
|
a0.5 mL doses contain 15 µg hemagglutinin of the vaccine strain A/California/7/2009
(H1N1)
bTwo doses separated by 4 weeks for children 2-9 years (CDC. Update on influenza
A (H1N1) monovalent vaccines. MMWR Morb Mortal Wkly Rep. 2009;58:1100-1101.)
NIH studies show
that the 15-µg dose without adjuvant generates an immune response that
is expected to be protective in most 10- to 17-year-olds at 8-10 days
post-vaccination. Younger children had the expected reduced response and
will require 2 doses separated by at least 21 days. Infants younger than
6 months are too young for influenza vaccines.
Inactivated
Intramuscular Vaccine
The inactivated
H1N1 vaccine uses killed virus and is intended to prevent 2009 H1N1 (not
seasonal flu) and is available in single dose or multidose vials. Some
inactivated 2009 H1N1 vaccines contain the preservative thimerosal. (Note
that some people have questioned a relationship between thimerosal and
autism, but a 2004 review by the Institute of Medicine found no association,
and subsequent studies have supported this conclusion. (Immunization Safety
Review Committee. Vaccines and Autism. Institute of Medicine. Washington,
DC: National Academies Press; 2004. Available at: http://www.nap.edu/catalog.php?record_id=10997
Accessed October 5, 2009.) The H1N1 vaccine will not prevent seasonal
flu, and seasonal flu vaccine will not prevent 2009 H1N1 influenza.
Children 6 months
to 9 years of age should receive 2 doses separated by 3 weeks. Children
10 years and older and adults should receive 1 dose.
The following
groups should receive the vaccine as soon as it becomes available:
- Pregnant women;
- People who live with or
care for infants younger than 6 months of age;
- Healthcare workers (HCWs)
and emergency medical personnel;
- Persons 6 months to 24
years of age;
- Persons 25-64 years of
age who have chronic diseases (including immunodeficiency states) that
pose risk for influenza.
When more vaccine becomes
available, the following persons should be vaccinated:
- Healthy persons ages 25-64
years; and
- Adults 65 years of age
and older.
Patients on the high-priority
list should be vaccinated as soon as the vaccine is available. Individuals
with the highest priority, as listed above, should be vaccinated first,
but stringency of methods to restrict vaccine use is unclear.
Contraindications to the inactivated
vaccine include:
- Previous Guillain-Barré
syndrome;
- Life-threatening reaction
to previous influenza vaccination; and
- Severe illness (a "moderately
or severely ill" patient is advised to wait, but a mild upper respiratory
infection or other illness is not a contraindication).
Note that pregnancy and breastfeeding
are not contraindications to receiving the inactivated vaccine. The most
common side effect with the killed virus vaccine is soreness at the injection
site. Concurrent administration with other vaccines is not contraindicated;
seasonal influenza vaccine may be given simultaneously with H1N1 influenza
vaccine.
Live Attenuated Nasal Spray
Vaccine
The second vaccine is a live
attenuated influenza (LAIV), which is given intranasally. LAIV does not
contain thimerosal. It is produced the same way as the LAIV that is used
for seasonal flu. It is expected that the LAIV for H1N1 influenza will
be as safe and effective as the LAIV for seasonal flu. This vaccine will
not prevent seasonal flu, and the seasonal flu vaccine will not prevent
2009 H1N1 influenza.
The LAIV for H1N1 is delivered
by a nasal spray as a single dose. It is FDA- approved for people 2-49
years of age who do not have contraindications. Groups who should receive
the LAIV include:
- Persons 2-24 years of age;
- Persons 25-49 years of
age who live with or care for infants younger than 6 months; and
- Persons 25-40 years of
age who are HCWs or emergency medical personnel.
When more vaccine becomes
available it should be offered to healthy persons ages 25-49 years who
do not have contraindications to the vaccine.
Contraindications to the LAIV
include:
- Severe allergy to eggs
or other vaccine ingredients;
- Age 2 years or younger
or 50 years or older;
- Immunosuppression;
- Chronic medical conditions,
including diseases of the heart, lung, kidney, or liver; diabetes, asthma,
or blood disease;
- Children younger than 5
years who have asthma or who have had an episode of wheezing in the
past year;
- Nervous system disease
that can cause breathing or swallowing problems;
- Children and adolescents
on long-term aspirin treatment;
- Any person who has close
contact with a person with a severe immunodeficiency;
- Persons with moderate or
severe illness should delay use of this vaccine (a mild upper respiratory
infection or similar illness is not a contraindication); and
- Unlike the inactivated
intramuscular vaccine, the 2009 H1N1 LAIV vaccine should not be given
with seasonal LAIV because the 2 live virus vaccines must be separated
by 1 month. It is permissible to give a killed virus vaccine like the
2009 H1N1 IM vaccine or the seasonal flu IM vaccine with a single LAIV.
Risks and side effects of
the LAIV:
- The most common side effect
with the live attenuated nasal spray is nasal congestion in all patients,
sore throats in adults, and fever in children 2-6 years.
- Some children 2-17 years
have mild reactions, including nasal congestion, headache, myalgias,
fever, wheezing, cough, or gastrointestinal symptoms.
- Some adults 18-49 years
have nasal congestion, cough, fatigue, myalgias, sore throat, or headache.
Comparative Efficacy of
Live Attenuated Influenza Vaccine and Inactivated (Killed Virus) Influenza
Vaccine
A double-blind, placebo-controlled
trial comparing the LAIV vaccine and the inactivated influenza virus vaccine
was conducted in 2007-2008 when influenza A (H3N2) accounted for 91% of
influenza cases and type B accounted for 9%. There were 1952 participants
ages 18-49 years assigned to receive the inactivated vaccine (or placebo)
by IM injection or the live virus vaccine (or placebo) by nasal spray.
Efficacy was based on frequency of an influenza-like illness that was
confirmed as influenza A or B by culture or PCR. The results showed that
absolute efficacy against influenza A was 72% for the killed virus vaccine
(IM injection) vs 29% for live virus vaccine (nasal sniff). The investigators
concluded that the inactivated vaccine was superior to the LAIV for preventing
Influenza A (H3N2) in adults. (Monto A, Ohmit SE, Petrie JG, et al. Comparative
efficacy of inactivated and live attenuated influenza vaccines. N Engl
J Med. 2009;361:1260-1267.)
| IOMS
Newsletter - 20 November 2009 |
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Issue
No. 003/09
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