Update - 4/2/13 10:52 PM

Bird Flu has infected four new patients in addition to the three bird flu cases previously announced by the Chinese government. The New York Times reports all four are critically ill and suffering from the new bird flu strain designated H7N9. The H7N9 strain of bird flu has no vaccine.

A new strain of bird flu virus has killed at least two in China, say government authorities. The new bird flu strain is communicable to humans, but the Chinese government waited 20 days before announcing the first fatalities. A Chinese woman also infected with bird flu remains hospitalized.

Similar symptoms reportedly afflicted all three. It's unclear when the bird flu diagnosis was made, but the H7N9 strain has not been seen previously in humans and Chinese officials say they don't know how the virus was contracted.

According to China's health commission, the new strain isn't easily transmitted and it's unclear how the two men were infected, but the delay in reporting the bird flu deaths fueled speculation of a cover-up. The only symptoms mentioned by Chinese officials were a high fever and cough.

The H7N9 strain of avian influenza is new and China has been tightlipped so far, but the most significant unknown is the flu's infection vector. Eighty-eight people shared contact with the infected men and none have developed flu symptoms so far. Nonetheless, without knowing how the flu virus is transmitted, containing it becomes problematic.

The new strain apparently has the same symptoms as regular bird flu, which is more or less the same as conventional influenza. In addition to a high fever and coughing, symptoms include throat soreness, muscle aches, vomiting and diarrhea. In some cases, a mild eye infection is the virus' only visible symptom.

According to the Mayo Clinic, you should see a doctor immediately if you develop a fever, cough or body aches and have recently traveled to a region where bird flu cases have been recorded.