Varicella vaccine
Varicella vaccine, also known as chickenpox vaccine, is a vaccine that protects against chickenpox. One dose of vaccine prevents 95% of moderate disease and 100% of severe disease. Two doses of vaccine are more effective than one. If given to those who are not immune within five days of exposure to chickenpox it prevents most cases of disease. Vaccinating a large portion of the population also protects those who are not vaccinated. It is given by injection just under the skin.
The World Health Organization (WHO) recommends routine vaccination only if a country can keep more than 80% of people vaccinated. If only 20% to 80% of people are vaccinated it is possible that more people will get the disease at an older age and outcomes overall may worsen. Either one or two doses of the vaccine is recommended. In the United States two doses are recommended starting at twelve to fifteen months of age. As of 2012 most European countries either recommend it for all children or just those at high risk, but not all countries provide the vaccine due to its cost.
Minor side effects may include pain at the site of injection, fever, and rash. Severe side effects are rare and occur mostly in those with poor immune function. Its use in people with HIV/AIDS should be done with care. It is not recommended during pregnancy; however, the few times it has been given during pregnancy no problems resulted. The vaccine is available either by itself or along with the MMR vaccine, in a version known as the MMRV vaccine. It is made from weakened virus.
The chickenpox vaccine first became commercially available in 1984. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. In the United States it costs between 100 and 200 USD.
Fujian flu
According to the New York Times: "[P]oultry vaccines, made on the cheap, are not filtered and purified [like human vaccines] to remove bits of bacteria or other viruses. They usually contain whole virus, not just the hemagglutinin spike that attaches to cells. Purification is far more expensive than the work in eggs, Dr. Stöhr said; a modest factory for human vaccine costs $100 million, and no veterinary manufacturer is ready to build one. Also, poultry vaccines are "adjuvated" — boosted — with mineral oil, which induces a strong immune reaction but can cause inflammation and abscesses. Chicken vaccinators who have accidentally jabbed themselves have developed painful swollen fingers or even lost thumbs, doctors said. Effectiveness may also be limited. Chicken vaccines are often only vaguely similar to circulating flu strains — some contain an H5N2 strain isolated in Mexico years ago. 'With a chicken, if you use a vaccine that's only 85 percent related, you'll get protection,' Dr. Cardona said. 'In humans, you can get a single point mutation, and a vaccine that's 99.99 percent related won't protect you.' And they are weaker [than human vaccines]. 'Chickens are smaller and you only need to protect them for six weeks, because that's how long they live till you eat them,' said Dr. John J. Treanor, a vaccine expert at the University of Rochester. Human seasonal flu vaccines contain about 45 micrograms of antigen, while an experimental A(H5N1) vaccine contains 180. Chicken vaccines may contain less than 1 microgram. 'You have to be careful about extrapolating data from poultry to humans,' warned Dr. David E. Swayne, director of the agriculture department's Southeast Poultry Research Laboratory. 'Birds are more closely related to dinosaurs.'" Researchers, led by Nicholas Savill of the University of Edinburgh in Scotland, used mathematical models to simulate the spread of H5N1 and concluded that "at least 95 per cent of birds need to be protected to prevent the virus spreading silently. In practice, it is difficult to protect more than 90 per cent of a flock; protection levels achieved by a vaccine are usually much lower than this."