Influenza Vaccine in Scleroderma Clinical Trial
Official title:
Safety and Efficacy of Vaccination Against Influenza in Patients With Scleroderma
The safety and efficacy of vaccination against influenza in patients with scleroderma is not clear. The objective of this study is to assess its safety and efficacy in 50 patients with scleroderma in comparison with 30 controls
Fifty patients with scleroderma and 30 healthy , aged matched controls will participate in
the study.
After signing informed consent, all subjects will be vaccinated with the inactivated split
virion vaccine which recommended by the WHO this fall.
Patients will be evaluated at weel 0 and 6 weeks later. Clinical evaluation will be based on
the modified Rodnan score, number of digital ischemic ulcers, presence of gastrointestinal
and respiratory symptoms, number of swollen and tender joints, visual global evaluation of
the physician , ESR and CRP Blood with be collected on the day of vaccination and 6 weeks
later.
The immunogenicity of the vaccine will be tested by Haemagglutination inhibition (HI) test.
Influenza virus has two important surface glycoproteins: the haemagglutinin (HA) and the
neuraminidase (NA). Antigenic classification and subtyping of influenza viruses is based on
these two glycoproteins. HA plays a key role in virus cell entry by binding to cell surface
receptors, which are found also on red blood cells of certain species. Binding to red cells
results in haemagglutination, which can be observed as a carpet of agglutinated red cells at
the bottom of a tube or microtitre well. In the HI test, antibody directed against the viral
haemagglutinins block the virus from binding to the blood cells and thus inhibits the
haemagglutination reaction.
The pre- and post immunization HI antibodies were tested at the Central Virology Laboratory
of the Israeli Ministry of Health using the HI test according to a standard WHO procedure
16. Sera were separated, code labeled, and stored at -20°C until tested. Sera were treated
with receptor destroying enzyme cholera filtrate to remove non-specific inhibitors, and with
Turkey red blood cells to remove non-specific agglutinins. The treated sera were tested by
HI test against the three antigens included in the vaccine: A/California (CAL), A/Wisconsin
and B/Malaysia. The working dilution (test dose) of each antigen contained four
haemagglutinin units in 25 µl of antigen. Test doses were diluted in phosphate buffered
saline (PBS) and added to serial dilution of antiserum. The haemagglutinin inhibition titer
was determined as the highest dilution of serum that completely inhibits haemagglutination
of red blood cells.
The titer of an antiserum not showing any inhibition will be recorded as <10. Humoral
response will be defined as either a fourfold or more rise in titer, or a rise from a
non-protective baseline level of <1/40 to 1/40 in HI antibodies four weeks after vaccination
17,18. Geometric mean titers of antibody will be calculated to assess the immunity of the
whole group.
Primary Endpoint of the study : the proportion of patients who achieve a titer of antibodies
above 1/40, against each of the antigens included in the vaccine Secondary Endpoint: Safety
of the vaccine
;
Allocation: Non-Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Prevention