Recently, the news that a "SARS (Severe Acute Respiratory
Syndromes) vaccine had entered into a stage of human testing"
aroused wide interest from the media and the public. Many people
offered to take part in the test for free. Questions such as the
selection standard of volunteers, testing methods as well as the
possible risks they face have become the most concerned questions
of volunteers. Here some of the questions are answered.
1.?What's the selection standard of
volunteers?
Volunteers are young and middle-aged people of a normal healthy
status.
So far, relative departments haven't formally publicized the
detailed health standards for volunteers taking part in the SARS
vaccine test. Although according to Guangdong Disease Prevention
and Control Center, they haven't got the formal notice of
recruiting volunteers for the test, it is reported the recruitment
of volunteers will mainly focus on Beijing and Guangdong because
these two places were the most severe SARS-affected areas, no
matter if in terms of the number of SARS patients, suspected cases
or those who had had contact with SARS patients.
A SARS research expert gave a description of a volunteer profile
when interviewed by a reporter from the Beijing Youth
Daily: first of all, the volunteer must be healthy without any
symptoms of catching a cold or fever or any other abnormal
symptoms. The recruitment will focus on young and middle-aged
people and give attention to people of other age groups as well.
According to the previous experience of vaccine testing on humans,
the volunteer must have a "normal healthy status", meaning not
especially strong or especially weak. Only by this will the test
results have universality.
2.?What methods will the test use?
One will be to check whether antibodies occur after inoculation.
Another is a comparison experiment.
In what way will volunteers take part in the test? According to
work staff in the administrative office of Guangdong Disease
Prevention and Control Center, theoretically, there are two ways
for some kind of vaccine to be used on human testing: one is to
inoculate the vaccine into the body of the volunteer and observe if
the human body will produce antibodies to the virus; the second is
a comparison test, that will divide volunteers into two groups, one
group being vaccinated, the other group not? vaccinated, and
then observe if the two groups of people have the same reaction
towards the virus under the same conditions. If the infection rate
of those vaccinated people reduces greatly, it means the vaccine is
effective.
"It is only theory," explained a staff member. "As to whether
the SARS vaccine test on humans will take the two methods at the
same time, it has not been confirmed yet. However, the first kind
of test (on blood serum) is necessary. And it will be more
difficult to conduct a comparison test. In addition, China has
always been very prudent on vaccine testing on humans since it is
closely related to our traditional morality and ethics."
Guangdong Disease Prevention and Control Center briefed on the
previous promotion procedures of the measles vaccine. After the
measles vaccine was developed, only people in a few experimental
areas had been chosen to accept the inoculation. After a period of
time of observation, the incidence of measles in the experimental
areas was much lower than other non-experimental areas. Then the
vaccine was gradually extended to other areas. And after many
years' research, only when it was proved that the vaccine had no
side-effects on children, China started to vaccinate new born
babies around the country.
3.?Will "lab infection accident of Singapore"
reoccur in China?
Inactivated vaccine is totally different from the virus used for
research and will not cause a SARS infection.
Many readers have called to ask about a SARS researcher in
Singapore that had been infected with the SARS virus. Would such a
thing reoccur in this test on humans? "Absolutely not," confirmed
staff in Guangdong Disease Prevention and Control Center.
She explained that generally the vaccines are divided into two
categories, one is an inactivated vaccine -- obtaining the virus
and handling it with a scientific method, makes the virus totally
lose its potency that allows it to be inoculated into an organism.
The pathogen microbes in it produce no damage to the organism. And
the organism will have an immune reaction towards the antigen
structure on the surface of the pathogen microbes. Another kind is
an attenuated vaccine, where some of the virus, after being
inactivated and inoculated into the body, cannot help the body to
prevent the disease. On the contrary, it worsens the patient's
condition when the virus invades. Therefore, more time has to be
spent on researching and developing an attenuated vaccine, that
will make the virus propagate for many generations, sometimes even
over hundreds of generations, and gradually get rid of the virus,
and make it into a vaccine. Therefore the attenuated vaccine has
higher requirements on the technical level.
According to Guangdong Disease Prevention and Control Center,
the "prime criminal" which caused the SARS infection of a
researcher in Singapore is a SARS virus used for research in the
lab, and what we call the "wild virus", which has a very strong
infection rate and propagation ability. It is totally different
from the vaccine we are now talking about.
It is reported that currently the SARS vaccine for human testing
that is approved by relative departments all belong to inactivated
vaccines.
4.?When can we say a SARS vaccine has been
successfully developed?
After human testing, it has to stand the test of clinical
application.
A SARS vaccine entering into a stage of human testing does not
mean the vaccine has been successfully developed.
According to relative experts, the testing of ordinary vaccines
must go through three stages: one, animal testing that inoculates
the vaccine into an animal and then inoculates the SARS virus and
observes the interdictive effect of the vaccine towards the virus.
Currently, China has finished the research of this stage. The
second stage is to test the vaccine on volunteers. The third is
clinical testing, which is the key stage of testing if the vaccine
has been successfully developed or not. Generally speaking, it
should take two years.
According to experts, the developed vaccine must also pass one
examination of an epidemic disease after going through the
aforesaid three stages. Only if it is proved to be able to prohibit
the spread of the virus and guarantee the health of humans, can it
reach the application period of batch production. Even at the
application stage, the vaccine is not absolutely safe without any
problems. The prevention rate of general vaccines is hard to reach
100 percent. The prevention rate of most vaccines is over 90
percent, even if the very successfully developed vaccine may be
effective in this group of 100 people, but only effective to 90 or
98 people among another group.
Facing the great concerns of the public towards the SARS
vaccine, Guangdong Disease Prevention and Control Center also
reminded that the SARS vaccine test on humans is a serious matter,
even if finally the vaccine is successfully developed,?
thinking of SARS as "no longer coming back" is not realistic.
For an infectious disease, besides preventive inoculation,
comprehensive prevention measures are very important. That is why
relative departments are speeding up the establishment of the
public health system, seizing every minute to study a SARS
vaccine.
(China.org.cn by Wang Qian and Daragh Moller, December 2,
2003)
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