BCG vaccine nesting birds and rusted electrical conduits. The resulting closure of the plant for over two years resulting in shortages of bladder cancer and tuberculosis vaccines. On October 29, 2014 Health Canada gave the permission for Sanofi to resume production of BCG. The global supply situation was analyzed in 2017 and concluded that the global supply is sufficient to meet forecasted BCG vaccine demand but risks for shortages remain mainly due to supply concentration. A weakened strain of bovine tuberculosis bacillus, "Mycobacterium bovis" is specially subcultured in a culture medium, usually Middlebrook 7H9. Some BCG vaccines are freeze dried and become
Inoculation Needham states that this information comes from the "Zhongdou xinfa" (種痘心法) written in 1808 by Zhu Yiliang, centuries after the alleged events. The first clear and credible reference to smallpox inoculation in China comes from Wan Quan's (1499–1582) "Douzhen xinfa" (痘疹心法) of 1549, which states that some women unexpectedly menstruate during the procedure, yet his text did not give details on techniques of inoculation. Inoculation was first vividly described by Yu Chang in his book "Yuyi cao" (寓意草), or "Notes on My Judgment", published in 1643. Inoculation was reportedly not widely practised in China until the reign of the Longqing