Answer:
Thesis statement: Based on the information presented in the excerpt, the passage appears to be credible and objective.
The passage provides information about the process of creating flu vaccines and the challenges involved in predicting the strains of viruses that will circulate in the following winter. The author cites the World Health Organization (WHO) as the organization responsible for predicting these strains, and acknowledges that the process can be affected by mutations in the viruses.
This information appears credible, as it is based on the statements of a reputable source, the CDC Director Tom Frieden, and acknowledges the uncertainties involved in predicting flu strains. Additionally, the passage provides specific details about the timing of the detection of the current variant strains, which suggests that the author has done research to support their claims.
One counter-argument to the credibility of the passage might be that it does not provide enough information to fully evaluate the claims being made. For example, the passage does not provide information about the methodology used by the WHO to predict flu strains, or the degree of accuracy of these predictions in previous years. Without this additional information, it is difficult to fully evaluate the credibility of the claims being made.
Overall, however, based on the information presented in the excerpt, the passage appears to be credible and objective. The author cites reputable sources, provides specific details to support their claims, and acknowledges the uncertainties involved in predicting flu strains.