To the editor, The Middle East respiratory syndrome coronavirus (MERS-CoV), along with the severe acute respiratory syndrome coronavirus (SARS-CoV), and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are three emerging coronaviruses with significant public health implications in the 21st century. SARS-CoV-2, in particular, has caused an unprecedented global pandemic, spreading to over 200 countries. As of the manuscript submission date, more than 450 million people were infected with SARS-CoV-2, with nearly 6 million of those infected dying (The data from World Health Organization).The origin (bat, snake, and pangolin) of SARS-CoV-2 has been debated since its first discovery in humans. [1][2][3][4] Although probable batorigin SARS-CoV and human-origin SARS-CoV-2 had 96% nucleotide similarity, they were not the same virus. More and more human-toanimal transmissions of SARS-CoV-2 have been reported in several countries over time. 5 This study performed a meta-analysis about natural infections of SARS-CoV-2 in animals. In detail, PubMed, a widely concerned database, was used. The systematic search was performed using a group of (medical subject headings, MeSH) terms and text words, such as (Covid OR SARS-CoV-2) AND (animal OR pet OR animal infection OR cat OR dog OR ferret OR tiger OR lion OR deer OR other animals). From January 1, 2020, to December 31, 2021, 9967 papers were searched. Finally, 105 papers about SARS-CoV-2 natural infection in animals were collected and used for analysis. With every half year as a calculation cycle, the number of published papers in PubMed gradually increased (Figure 1A). Serological, molecular, and double evidence were linked to 32, 26, and 47 papers, respectively.The cat (39/105 papers) was the most common natural infection host among infected animals. Cats and dogs were still the main natural infection hosts in 26 multispecies studies (Figure 1B). These findings suggested that cats and dogs may be particularly vulnerable to SARS-CoV-2 infection. 5,6 Most papers came from American and European countries (Figure 2), consistent with the current coronavirus disease 2019 (COVID-19) epidemic. Almost all animal infections in these natural SARS-CoV-2 infection studies were caused by infected humans. It is worth | 3503 In conclusion, SARS-CoV-2 is found widely in humans, animals, and the environment. Humans are the most important factor in SARS-CoV-2 control. We can discover a transmission route, control the infection, and develop vaccines and antiviral drugs. However, in addition to ongoing trade and migration in different countries and regions, the viral mutation increases, contributing to the spread of SARS-CoV-2. Perhaps, we will continue to fight SARS-CoV-2 in the coming years.