COVID-19 – what is the primary infection point?

Notes from Dr AG Andjaparidze (

Copied and pasted here from his FB posting with his permission:

Dear friends,
I am a virologist who discovered two viruses, Hepatitis E virus and Semen Hepatitis A virus. I belong to the old medical virology school, which considers it of fundamental importance to determine where virus replication starts and how it is discharged from the infected person.
In addition to medical virology experience, I also had a chance to serve more than 20 years with WHO SEARO as communicable diseases adviser. I have first-hand experience preventing and controlling many parasitic, bacterial and viral infections. My retired WHO and research colleagues have encouraged me to share with you some of my speculation regarding COVID19.

We all know respiratory and alimentary tracts are common sites for viral entry. Many viruses can infect susceptible cells of both tracts. In 1983, I had detected coronavirus particles in stool samples in children with dual unknown respiratory and gastrointestinal mild symptoms. However, no further studies or discussions regarding coronavirus replication has been carried out (1).

All known seven coronaviruses have been identified as a causative agent of mild (HCoV-229E; HCoV-OC43; HCoV-NL63 and HCoV-HK11) severe (SARS-CoV; MERS- CoV and finally COVID 19) respiratory infections.
Gastrointestinal symptoms in up to 57% of patients with coronavirus HCoV-OC43 is well documented (2). Gastrointestinal symptoms are also presented in patients with SARS-CoV(3). Active virus replication was identified in the small and large intestine specimens from colonoscopy biopsy and autopsy (4). A significant portion of SARS patients had gastrointestinal symptoms; the viral load was the highest in stool specimens followed by nasopharyngeal aspiration specimens (3).

In 2004 Ding Y. and colleagues speculated that the human gastrointestinal tract could be the primary infection site of SARS-CoV, which raised a fearsome concern of SARS-CoV’s dual infectivity as being both a respiratory and gastrointestinal pathogen (4).
It is known that most animal coronaviruses, such as bovine coronavirus and porcine transmissible gastroenteritis virus, can primarily infect either the enteric or respiratory tract or sometimes can be translocated between sites (5,6)

In 2017 Jie Zhou and colleagues demonstrated that the human intestinal tract serves as an alternative infection route for MERS-CoV(7).
Analyzing China’s current epidemiological situation, various reports, new and old publications regarding coronaviruses and COVID 19 provide important information. Based on that, we have to consider the following:

A. Possibly COVID 19 can primarily infect either enteric or respiratory tract. (Further studies will determine if there is any difference in clinical manifestation among patients with primarily enteric infection and primarily respiratory tract infection. I expect primarily enteric tract infection will be mild, and respiratory tract infection will be more severe.)

B. Body fluids, nasopharyngeal discharge and faeces of a patient with COVID 19 infection are a major source of infection.

C. Possibly CIVID 19 patient’s stool could be a major source for the faecal-oral route of transmission of this infection.

This is all that I would like to share with you. In case you think my speculation is useful please share this information with health authorities at national and international level.
Best regards,
Alex (retiree)


1 .A.G.Andjaparidze, M.S.Balayan, S.S. Savinskaya, M.K.Mamedov, A.E.Annenkov, N.A. Goryunova- Viruses in feces from patients with viral hepatitis and other enterovirus infections –“Voprosi Virusologii”,1984,6.p 559-566.
2. Vabret A., Mourez T., Gouarin S., Petitjean J., Freymuth F., An outbreak of coronavirus OC43 respiratory infection in Normandy, France. Clin. Infect. Dis. 36, 985–989 (2003).

3. Peiris J. S. M., Lai S. T., Poon L. L. M., Guan Y., Yam L. Y. C., Lim W., Nicholls J., Yee W. K. S., Yan W. W., Cheung M. T., Cheng V. C. C., Chan K. H., Tsang D. N. C., Yung R. W. H., Ng T. K., Yuen K. Y.: SARS study group, Coronavirus as a possible cause of the severe acute respiratory syndrome. Lancet 361, 1319–1325 (2003).

4. Leung W. K., To K.-f., Chan P. K. S., Chan H. L. Y., Wu A. K. L., Lee N., Yuen K. Y., Sung J. J. Y., Enteric involvement of severe acute respiratory syndrome-associated coronavirus infection. Gastroenterology 125, 1011–1017 (2003).

5 . Hung I. F. N., Cheng V. C. C., Wu A. K. L., Tang B. S. F., Chan K. H., Chu C. M., Wong M. M. L., Hui W. T., Poon L. L. M., Tse D. M. W., Chan K. S., Woo P. C. Y., Lau S. K. P., Peiris J. S. M., Yuen K. Y., Viral loads in clinical specimens and SARS manifestations. Emerg. Infect. Dis. 10, 1550–1557 (2004).

6 . Ding Y., He L., Zhang Q., Huang Z., Che X., Hou J., Wang H., Shen H., Qiu L., Li Z., Geng J., Cai J., Han H., Li X., Kang W., Weng D., Liang P., Jiang S., Organ distribution of severe acute respiratory syndrome (SARS) associated coronavirus (SARS-CoV) in SARS patients: Implications for pathogenesis and virus transmission pathways. J. Pathol. 203, 622–630 (2004).

7. Jie Zhou, Cun Li, Guangyu Zhao, Hin Chu, Dong Wang, Helen Hoi-Ning Yan, Vincent Kwok-Man Poon, Lei Wen, Bosco Ho-Yin Wong, Xiaoyu Zhao, Man Chun Chiu, Dong Yang,Yixin Wang, Rex K. H. Au-Yeung, Ivy Hau-Yee Chan, Shihui Sun, Jasper Fuk-Woo Chan, Kelvin Kai-Wang To,Ziad A. Memish, Victor M. Corman, Christian Drosten,11,12 Ivan Fan-Ngai Hung,13 Yusen Zhou,4,† Suet Yi Leung,5 and Kwok-Yung Yuen – Human intestinal tract serves as an alternative infection route for Middle East respiratory syndrome coronavirus Sci Adv. 2017 Nov; 3(11): eaao4966. Published online 2017 Nov 15. doi: 10.1126/sciadv.aao4966