https://www.covid19treatmentguidelines.nih.gov/tables/table-...
Because the treatments that work (ie: Monoclonal Antibodies) are being hugely invested into right now. IIRC, the government just spent a few billion dollars buying more doses of them.
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The thing about COVID19 vaccine boosters is that the CDC has basically blessed them, but the FDA has not yet. As such, there's a vigorous debate going on right now whether the 3rd dose is needed. (Immunocompromised individuals are already allowed to get the 3rd dose however. The only questions with regards to the booster is the general public). Yes, different agencies will disagree on things. CDC is most focused on public health, FDA is most focused on safety. Their goals / purposes are different, and therefore will lead to situations where they disagree like this. The White House then has to resolve the difference and make a stance. Since the White House is having meetings on the subject, it makes the news a lot.
For some "alternative treatments", like Ivermectin, there's no major body who believes it works in the USA. CDC says it doesn't work. FDA says it doesn't work. NIH doesn't have any research showing any reasonable degree of efficacy.