From an analysis of the literature it is understood that there are major Antiviral effects of doxycycline. These effects are magnified by HydroxyChloroquine in other studies. Zinc has synergies With Doxycycline in the attack on the Virus As well as the CoInfection, Mycoplasma.
Given the risks of hydroxychloroquine and azithromycin in combination, we suggest hydroxychloroquine with doxycycline as a better alternative to azithromycin. Doxycycline and other tetracycline derivatives such as minocycline exhibit anti-inflammatory effects along with in vitro antiviral activity against several RNA viruses. Use of these agents have been associated with clinical improvement, even reversal of cytokine storm in some infections caused by RNA viruses, such as dengue fever [10].
The mechanism of the antiviral effects of tetracycline derivatives may be secondary to transcriptional upregulation of intracellular zinc finger antiviral protein (ZAP), an encoding gene in host cells [11,12]. ZAP can also bind to specific target viral mRNAs and represses the RNAs translation [13,14]. Experimental studies have used tetracycline to induce the overexpression of host ZAP in HEK293, rats and monkeys cell lines (Vero cells), which contributed to inhibition of RNA viruses such as the Dengue, Ebola, Human Immunodeficiency Virus, Zika, and Influenza A viruses [11,12,[15], [16], [17], [18]].
Also, in vitro studies have showed that doxycycline can repress Dengue virus infection in Vero cells through the inhibition of dengue serine protease enzymes and of viral entry [17,19]. Doxycycline showed the capacity to inhibit dengue virus replication in Vero cells culture and likely it interacts with the dengue virus E protein that is required for virus entry [19]. Similarly, doxycycline controls Chikungunya virus (CHIKV) infection through the inhibition of CHIKV cysteine protease of Vero cells and showed significant reduction of CHIKV blood titer of mice [20].
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7298522/
