Like for all other
licensed medicines, the safety of these vaccines is being monitored by agency's
Pharmacovigilance Risk Assessment Committee (PRAC). The present review will
delve into the available data with focus on rare reports on two conditions:
CRPS (complex regional pain syndrome), a chronic pain condition affecting the
limbs and POTS (postural orthostatic tachycardia syndrome), a condition where
heart rate increases abnormally following sitting or standing up, thereby
causing symptoms like dizziness, fainting, headache, chest pain and weakness.
The above conditions
have been previously reported in young women who have received an HPV vaccine.
The report was then considered by the PRAC during routine safety monitoring.
But, no causal relationship was established between the conditions and vaccines
taken. These conditions can however also occur in non-vaccinated individuals
too and it is therefore considered imperative for further review to assess if
number of cases reported with
HPV vaccine is
greater than expected.
The review of HPV
vaccines has been commenced by the European Commission at the request of
Denmark, under Article 20 of Regulation (EC) No 726/2004. The review would be
carried out by PRAC (the Committee responsible for the evaluation of safety
issues for human medicines), who will be making a set of recommendations. In its
review, PRAC will be considering the latest scientific knowledge, including any
research that would help to elucidate the frequency of CRPS and POTS after
vaccination or identify causal link if any. Based on this review, the committee
would decide to recommend any changes to product information so as to better
inform patients and healthcare professionals. However, under ongoing review
there is no change in recommendations in use of the vaccines.
The recommendations
made by PRAC will then be forwarded to the Committee for Medicinal Products for
Human Use (CHMP), which is responsible for questions related to medicines for
human use. The CHMP will then adopt a final opinion. The concluding stage of
this review process would be decision adoption by the European Commission,
which would be applicable to all European member states.
What
are Human Papillomaviruses?
Human papillomavirus
(HPVs) constitute a group of more than 200 related viruses. HPV of more than 40
different types can be easily transferred by direct sexual contact from skin
and mucous membranes of people who are infected to the skin and mucous
membranes of their spouse/partners. In addition, it can be spread by vaginal,
anal and
oral sex. Other HPV
types responsible for non-genital warts are not sexually transmitted.
Sexually transmitted
HPV is
of two types:
Low-risk HPVs (which
are not cancer causing) and
High-risk
HPVs (cancer causing). High-risk
HPVs cause several types of cancer namely cervical cancer (caused by types 16
&18); anal cancer (caused by type 16); oropharyngeal cancer (caused by type
16);rarer cancers like vaginal
cancer, vulvar cancer, penile cancer (caused by type 16).
About the Vaccines
In the European Union
HPV vaccines are available under the names Gardasil/Silgard, Gardasil 9, and
Cervarix. Gardasil has been approved for usage since September 2006 in both
males and females to prevent precancerous growths and cancer in the cervix and
anus, and
genital warts.
Gardasil protects against 4 types of HPV (types 6, 11, 16 and 18). Gardasil 9,
approved in June 2015 is used similarly and protects against 9 virus types
namely 6, 11, 16, 18, 31, 33, 45, 52 and 58. Cervarix was approved in September
2007 for use in women and girls to guard against precancerous growths and
cancer of the cervix and genital area. It also protects against types 16 and 18
virus forms. Subsequent to their approval, these vaccines have been introduced
in national immunization
programs in several countries worldwide.
How
do HPV Vaccines Act?
HPV vaccines work by
stimulating the antibody production. HPV vaccines are based on virus-like particles (VLPs) formed by HPV
surface components. VLPs are not infectious as it lacks the viral DNA, but, they look like natural virus. Antibodies produced against VLPs act against the natural virus. VLPs are also immunogenic, as it
induces a high
level of antibody production,
thus
making vaccines highly effective.
Safety
& Efficacy of HPV Vaccines
As of now no serious
side effects have been observed. Most common problems are brief soreness and
local symptoms at the injection site. These vaccines are contraindicated in
pregnancy as pertinent safety data is currently unavailable. Patients using
Gardasil vaccine have reported a higher proportion of syncope
(fainting) and venous thrombotic
events (blood clots) as compared to other vaccines. It was also seen that the
patients who developed blood clots had known risk factors for their
development, such as the use of oral contraceptives. However, safety review of
this particular vaccine in Denmark and Sweden did not identify an increased
risk of blood clots. HPV vaccines are highly effective in infection prevention
for the types of HPV it is being targeted.
References : 1. European Medicine Agency. Accessed July
24 2015. Available from: http://www.ema.europa.eu/ema/index.jsp?curl=pages/news_and_events/news/2015/07/news_detail_002365.jsp&mid=WC0b01ac058004d5c1
2. Human Papillomavirus (HPV) Vaccines.
National Cancer Institute. Accessed July 24 2015. Available from: http://www.cancer.gov/about-cancer/causes-prevention/risk/infectious-agents/hpv-vaccine-fact-sheet
Source: Medindia
