COVID-19-Associated Hospitalizations Among Adults During SARS-CoV-2 Delta and Omicron Variant Predominance, by Race/Ethnicity and Vaccination Status - COVID-NET, 14 States, July 2021-January 2022. Mutations in Omicron might increase transmissibility, confer resistance to therapeutics, or partially escape infection- or vaccine-induced immunity. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance. JAMA Pediatr. The decrease in isolation time was largely to decrease the impact and disruption of infection on day-to-day life and allow people to return to work sooner, Oller said. Our results might warrant a reduction of the quarantine period from 7 to 5 days during the BA.5dominant period in Japan (13). Classification of Omicron (B.1.1.529): SARS-CoV-2 variant of concern. Pulmonary Aspects of COVID-19. 2021/11/01/ 2021;27(11):1658-1665. doi:https://doi.org/10.1016/j.cmi.2021.05.040, Chandler CM, Reid MC, Cherian S, Sabath DE, Edlefsen KL. Apr 2021;27(4):626-631. doi:10.1038/s41591-021-01292-y, Daugherty SE, Guo Y, Heath K, et al. Pregnancy and postpartum outcomes in a universally tested population for SARS-CoV-2 in New York City: a prospective cohort study. Verywell Health's content is for informational and educational purposes only. If you need to go back and make any changes, you can always do so by going to our Privacy Policy page. Figures Figure. Delta's incubation period was about four days, . Implementation of concurrent prevention strategies, including vaccination, masking, improving ventilation, testing, quarantine, and isolation are recommended to slow transmission of SARS-CoV-2, including variants such as Omicron, to protect against severe illness and death from COVID-19. Bmj. Coronavirus (COVID-19) Infection Survey Technical Article: Impact of vaccination on testing positive in the UK. Diarrhea. The average duration of illness is shorter with Omicron than Delta: five days compared to six. The Lancet Regional Health - Europe. doi:10.1093/cid/ciac471, Godfred-Cato S, Abrams JY, Balachandran N, et al. (6,7) However, it is unclear what percentage of people who have asymptomatic infection progress to clinical disease (presymptomatic presentation). Even though the incubation period did not statistically differ, serial interval was significantly decreased in Omicron (mean 4.8 vs. 5.3, median 4 vs. 5) and was again more grouped to the left (IQR 3 vs. 5). For example, masks are required in indoor areas on public transportation conveyances traveling into, within, or out of the United States, and on the indoor premises of U.S. transportation hubs. Current travel requirements and recommendations,**** surveillance programs, and efforts to educate travelers are intended to reduce COVID-19 transmission and support safer global travel. Clin Infect Dis. Nebraska Cases of Omicron Suggest Short Incubation Period and Possibly Milder Disease. Omicron is swifter still, with an incubation period of roughly three days, according to a recent C.D.C. This policy was intended to reduce overall travel volume from the region where Omicron was first identified to delay the introduction and spread of Omicron while U.S. public health measures were enhanced. Trends in Treatments for Multisystem Inflammatory Syndrome in Children (MIS-C), United States, February 2020 - July 2021. They help us to know which pages are the most and least popular and see how visitors move around the site. J Ophthalmic Vis Res. The mean virus incubation period during the SARS-CoV-2 Omicron BA.5dominant period in Japan was 2.6 (95% CI 2.52.8) days, which was less than during the Delta-dominant period. A negative test result closer to the time of travel enhances reduction in transmission risk during travel (6). Thank you for taking the time to confirm your preferences. The mean virus incubation period during the SARS-CoV-2 Omicron BA.5-dominant period in Japan was 2.6 (95% CI 2.5-2.8) days, which was less than during the Delta-dominant period. An update on COVID-19 and pregnancy. N Engl J Med. Among the cases described in this report, the earliest report of symptom onset was November 15. Jun 2021;299(3):E262-e279. Lancet Glob Health. JAMA Network Open. Jan 2022;22(1):306-314. doi:10.1111/ajt.16641, Tenforde MW, Patel MM, Gaglani M, et al. Scientists around the world are working to rapidly learn more about the Omicron variant to better understand how easily it might be transmitted and the effectiveness of current diagnostic tests, vaccines, and therapeutics against this variant. Jan 27 2021;72(2):340-350. doi:10.1093/cid/ciaa863, Belsky JA, Tullius BP, Lamb MG, Sayegh R, Stanek JR, Auletta JJ. "Omicron has the shortest incubation period. Anyone exhibiting symptoms should get tested for COVID-19. The Journal of infection. BNT162b2 mRNA Vaccination Against COVID-19 is Associated with Decreased Likelihood of Multisystem Inflammatory Syndrome in U.S. Children Ages 5-18 Years. What is Omicron's incubation period? The Omicron variant has an incubation period of about three days, which is shorter than the incubation period for other variants of the virus that cause COVID-19. Genomic sequencing detected variants of concern in Japan from July 19September 13, 2001, as follows: 26,963 cases of B.1.617.2 (Delta), 15,009 cases of B.1.1.7 (Alpha), and 5 cases of other variants (9); the L452R mutation was found mostly in the Delta variant. Third, exposures from sources other than the infector of the pair might have been missed. If the pair shared meals on both July 4 and 5, we excluded all data from this pair. J Infect Dis. Omicron is thought to cause milder symptoms, according to early research.The CDC . Aug 2021;69(6):1253-1255. doi:10.1136/jim-2021-001853, Roskosky M, Borah BF, DeJonge PM, et al. Timely case investigation and contact tracing can help ensure compliance with isolation and quarantine guidance and link persons with positive SARS-CoV-2 test results and their close contacts to testing and supportive services. Centers for Disease Control and Prevention. Figure. MMWR Morb Mortal Wkly Rep. Jan 28 2022;71(4):146-152. doi:10.15585/mmwr.mm7104e4, Taylor CA, Whitaker M, Anglin O, et al. BA.5 is a subvariant of the SARS-CoV-2 Omicron variant (1). N Engl J Med. To accelerate detection of COVID-19 cases attributed to the Omicron variant until they are common enough to be reliably measured by routine genomic surveillance, enhanced surveillance was initiated through National SARS-CoV-2 Strain Surveillance on November 28. A vaccinated person had completed the primary series of a Food and Drug Administrationauthorized or approved COVID-19 vaccine 14 days before illness onset or receipt of a positive SARS-CoV-2 test result. CDC says the majority of virus transmission occurs one to two days before symptom onset and two to three days after. Finally, increasing patient numbers might have influenced the quality of contact tracing by the PHC. We defined patients in the Omicron BA.5dominant period as those who had symptoms during July 4August 19, 2022. Clin Infect Dis. Clin Infect Dis. . The incubation period might be influenced by various factors, such as viral load, environmental setting, patient immune response, severity of disease, and selection biases. Lancet Infect Dis. Incubation period correlated with shared meals and adult infectors. Through this program, international air travelers are offered molecular testing of pooled samples collected upon arrival and a take-home collection kit (saliva collection for nucleic acid amplification test) to be used 35 days after arrival with subsequent sequencing of SARS-CoV-2positive specimens; persons in pools with a positive test result are contacted and advised to get retested using the home collection kit or another method. CDC twenty four seven. Mar 2022;10(3):e326-e328. The first patient infected with SARS-CoV-2 Omicron BA.5 was reported on July 4, 2022, to the Itako PHC in Ibaraki Prefecture, Japan. 2022;149(1):e2021053418. Coagulation abnormalities and thrombosis in patients with COVID-19. Multisystem Inflammatory Syndrome in Children by COVID-19 Vaccination Status of Adolescents in France. JAMA Intern Med. Mar 2 2022;376:e068632. The 95th percentile distribution for incubation period among patients during the BA.5dominant period appeared shorter than that during the BA.1dominant period, although the difference was not statistically significant. Therefore, isolating for five days may not be enough, even if one is asymptomatic, Weiss said. Epidemiology of Infections with SARS-CoV-2 Omicron BA.2 Variant, Hong Kong, January-March 2022. Clinical Characteristics and Outcomes of Hospitalized Women Giving Birth With and Without COVID-19. Saving Lives, Protecting People, https://www.cdc.gov/coronavirus/2019-ncov/variants/spheres.html, https://covid.cdc.gov/covid-data-tracker/#variant-proportion, https://www.whitehouse.gov/briefing-room/presidential-actions/2021/11/26/a-proclamation-on-suspension-of-entry-as-immigrants-and-nonimmigrants-of-certain-additional-persons-who-pose-a-risk-of-transmitting-coronavirus-disease-2019, https://www.cdc.gov/quarantine/fr-proof-negative-test.html, https://www.cdc.gov/quarantine/order-collect-contact-info.html, https://www.cdc.gov/coronavirus/2019-ncov/php/contact-tracing/contact-tracing-plan/overview.html, https://www.cdc.gov/coronavirus/2019-ncov/your-health/quarantine-isolation.html, https://www.cdc.gov/quarantine/masks/mask-travel-guidance.html, https://www.cdc.gov/coronavirus/2019-ncov/travelers/international-travel/index.html, https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/scientific-brief-omicron-variant.html, https://www.who.int/news/item/26-11-2021-classification-of-omicron-(b.1.1.529)-sars-cov-2-variant-of-concern, https://covid-19.tacc.utexas.edu/media/filer_public/d9/d9/d9d99a16-704e-4c00-ab41-069957c6c25e/variant_calculator_user_guide.pdf, https://www.thermofisher.com/us/en/home/clinical/clinical-genomics/pathogen-detection-solutions/covid-19-sars-cov-2/multiplex.html, https://doi.org/10.1186/s12916-021-01975-w, https://www.nicd.ac.za/frequently-asked-questions-for-the-b-1-1-529-mutated-sars-cov-2-lineage-in-south-africa/, Centers for Disease Control and Prevention, U.S. Department of Health & Human Services, Shortness of breath or difficulty breathing. MMWR Morb Mortal Wkly Rep. Feb 4 2022;71(5):177-181. doi:10.15585/mmwr.mm7105e1, Olson SM, Newhams MM, Halasa NB, et al. Genomic evidence for reinfection with SARS-CoV-2: a case study. The incubation period of Omicron - the period from being infected to getting symptoms - is around three days, with the person often becoming infectious a day or two before symptoms emerge. The incubation period is the period from when a person becomes infected to when they start showing symptoms. The rapid antigen test may help gauge infectiousness: If a person tests positive, they should consider themselves contagious, he added. doi:10.1542/peds.2021-053418, Preston LE, Chevinsky JR, Kompaniyets L, et al. Incubation periods are still just an average, and infected people may develop symptoms anytime within two to 14 days after exposure. MMWR Morb Mortal Wkly Rep. Apr 30 2021;70(17):644-650. doi:10.15585/mmwr.mm7017e3, Chevinsky JR, Tao G, Lavery AM, et al. The CDC report also found that the incubation period for the omicron variant that is, the amount of time from when a person is infected to when symptoms begin appears to be shorter than . Dr. Roy Gulick, the chief of infectious diseases at Weill Cornell Medical Center and NewYork-Presbyterian, said typical symptoms of the omicron subvariants include: Sore throat. Virus Evol 2021;7:veab064. The symptoms of the latest omicron subvariants are mostly similar to those of the earlier version of omicron. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance. Shorter incubation period among COVID-19 cases with the BA.1 Omicron variant. Estimated overall mean incubation periods and means within percentiles for Omicron and Delta variants in study of SARS-CoV-2 incubation period during the Omicron BA.5-dominant period in Japan* *Values are mean no. Clin Infect Dis. By Carla Delgado Serial interval and incubation period of COVID-19: a systematic review and meta-analysis. CDC has a multifaceted surveillance system for analyzing SARS-CoV-2 variants circulating in the United States. Regarding the isolation period for COVID-19 generally, the CDC states that people must isolate for 10 days after symptoms first show up and can stop after that as long as they haven't had a. Interim clinical guidance for management of patients with confirmed coronavirus disease (COVID-19), What we know about quarantine and isolation, CDC updates and shortens recommended isolation and quarantine period for general population, High rates of rapid antigen test positivity after 5 days of isolation for COVID-19, Modeling the effect of age on quantiles of the incubation period distribution of COVID-19. Clinical manifestations, risk factors, and maternal and perinatal outcomes of coronavirus disease 2019 in pregnancy: living systematic review and meta-analysis. Cmaj. Other transmission settings included conversations in the home, a building or car, or outdoors. Acute covid-19 and multisystem inflammatory syndrome in children. Aug 2020;25(32)doi:10.2807/1560-7917.Es.2020.25.32.2001483, Eyre DW, Taylor D, Purver M, et al. EClinicalMedicine. Oct 3 2022;75(Supplement_2):S303-s307. Cookies used to enable you to share pages and content that you find interesting on CDC.gov through third party social networking and other websites. and/or the original MMWR paper copy for printable versions of official text, figures, and tables. Carla M. Delgado is a health and culture writer based in the Philippines. Euro Surveill. The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website. Landon E, Bartlett AH, Marrs R, Guenette C, Weber SC, Mina MJ. 2021;156(2):185-197. doi:10.1093/ajcp/aqab052, Levi M, Thachil J, Iba T, Levy JH. CDC is also supporting efforts to prevent, detect, and respond to COVID-19 internationally, including through support for laboratory and sequencing capacity and strengthening global vaccine programs. Will Omicron Show Up On Rapid COVID Tests? Lancet Reg Health Eur. Data from December 2021 suggests that Omicron's average incubation period is around two to four days, which would mean that symptoms may develop faster after exposure compared to other variants. Effect of Covid-19 Vaccination on Transmission of Alpha and Delta Variants. New England Journal of Medicine. Cookies used to enable you to share pages and content that you find interesting on CDC.gov through third party social networking and other websites. Clin Infect Dis. This prioritization should be balanced with maintaining case investigation and contact tracing for outbreaks of confirmed cases of SARS-CoV-2 infection in high-risk congregate settings (e.g., long-term care facilities, correctional facilities, and homeless shelters) and for persons at increased risk for severe COVID-19related health outcomes. We extracted data for 266 infector/infectee pairs who had 1 definite date of SARS-CoV-2 exposure as follows: 122 infectees from 108 infectors during the Omicron BA.5dominant period, 68 infectees from 49 infectors during the BA.1dominant period, and 76 infectees from 51 infectors during the Delta-dominant period. If you get infected with the Omicron variant, symptoms may occur within two to four days. The rapid emergence and worldwide detection of the SARS-CoV-2 Omicron variant underscores the importance of robust genomic surveillance systems and prompt information-sharing among global public health partners. We defined the patient with the later symptom onset in each pair as the infected patient. These cookies may also be used for advertising purposes by these third parties. Clin Infect Dis. May 19 2022;386(20):1899-1909. doi:10.1056/NEJMoa2202826, Zambrano LD, Ellington S, Strid P, et al. Clin Infect Dis. Updated Jan. 27, 2023 The omicron subvariant of COVID-19, BA.5, became one of the dominant strains of the virus in the fall of 2022 in the U.S. At that time, it was the most easily spread strain to date and is able to evade immunity from COVID infection and vaccination. Aug 1 2021;175(8):837-845. doi:10.1001/jamapediatrics.2021.0630, Miller AD, Zambrano LD, Yousaf AR, et al. Systematic review and meta-analysis of chest radiograph (CXR) findings in COVID-19. Among 43 cases with initial follow-up, one hospitalization and no deaths were reported. COVID-19 in immunocompromised patients: A systematic review of cancer, hematopoietic cell and solid organ transplant patients. Incubation periods for Omicron BA.1 were reported to be 3.3 days in Norway, 4.6 days in South Korea, 3.2 days in the Netherlands, 3.1 days in Spain, and 2.9 days in Japan (6,10,11); incubation period for BA.2 was 4.4 days in Hong Kong (12). MMWR Morb Mortal Wkly Rep. Jan 28 2022;71(4):125-131. doi:10.15585/mmwr.mm7104e1, Cavanaugh AM, Spicer KB, Thoroughman D, Glick C, Winter K. Reduced Risk of Reinfection with SARS-CoV-2 After COVID-19 Vaccination - Kentucky, May-June 2021. doi:10.1097/inf.0000000000003435, Marks KJ, Whitaker M, Agathis NT, et al. JAMA Netw Open. On December 10, 2021, this report was posted online as an MMWR Early Release. TaqPath COVID-19 Multiplex Diagnostic Solution. provided as a service to MMWR readers and do not constitute or imply You will be subject to the destination website's privacy policy when you follow the link. A new variant of SARS-CoV-2 (the virus that causes COVID-19), B.1.1.529 (Omicron) (1), was first reported to the World Health Organization (WHO) by South Africa on November 24, 2021. Clinical Presentation and Outcomes of Pregnant Women With Coronavirus Disease 2019: A Systematic Review and Meta-analysis. You can review and change the way we collect information below. These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. MMWR Morb Mortal Wkly Rep. Jul 16 2021;70(28):985-990. doi:10.15585/mmwr.mm7028a1, Wiltz JL, Feehan AK, Molinari NM, et al. Clin Microbiol Infect. Characteristics of Persons Who Died with COVID-19 - United States, February 12-May 18, 2020. Jan-Mar 2021;16(1):103-112. doi:10.18502/jovr.v16i1.8256, Tan E, Song J, Deane AM, Plummer MP. BMC Pregnancy Childbirth. Suggested Citation. A) Transmission period; B) incubation period; C) serial interval. part 46.102(l)(2); 21 C.F.R. Jun 1 2021;4(6):e2111182. 2020/08/01/ 2020;81(2):266-275. doi:https://doi.org/10.1016/j.jinf.2020.05.046, Gerver SM, Guy R, Wilson K, et al. 2020/09/01/ 2020;98:180-186. doi:https://doi.org/10.1016/j.ijid.2020.06.052, Yang J, Zheng Y, Gou X, et al. doi:10.1136/bmj.m3320, DeSisto CL, Wallace B, Simeone RM, et al. Nov 2020;127(12):1548-1556. doi:10.1111/1471-0528.16403, Siebach MK, Piedimonte G, Ley SH. COVID-19 Cases and Hospitalizations by COVID-19 Vaccination Status and Previous COVID-19 Diagnosis - California and New York, May-November 2021. MMWR Morb Mortal Wkly Rep. Jan 28 2022;71(4):118-124. doi:10.15585/mmwr.mm7104a2, Kwon JH, Tenforde MW, Gaglani M, et al. Preprint posted onlineFebruary 2, 2022. doi:10.1101/2022.02.01.22269931, Liu X, Wang L, Ma X, Wang J, Wu L. Modeling the effect of age on quantiles of the incubation period distribution of COVID-19. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website. Science brief: Omicron (B.1.1.529) variant. But it would help explain the variant's rapid spread. The clinical presentation of COVID-19 ranges from asymptomatic to critical illness. The risk of severe COVID-19 increases with increasing age over 40 years and with increasing number of certain, Shortness of breath or difficulty breathing. Probability densities for incubation period distribution during different SARS-CoV-2 variant-dominant periods in study of SARS-CoV-2 incubation period during the Omicron BA.5dominant period in Japan. CDC. Distribution of Omicron variant SARS-CoV-2 cases, Cantabria, Spain, December 2021. The number of confirmed COVID-19 cases from July 4 through August 19, 2022, was 12,577 in the PHCs jurisdiction, which has a population of 265,000 persons (5). Feb 10 2022;386(6):509-520. doi:10.1056/NEJMoa2116044, Sjoding MW, Dickson RP, Iwashyna TJ, Gay SE, Valley TS. Lancet. Risk Factors for Intensive Care Unit Admission and In-hospital Mortality among Hospitalized Adults Identified through the U.S. Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET). International Journal of Infectious Diseases. Symptoms can overlap with those of other viral respiratory illnesses. Maternal, fetal and neonatal outcomes of large series of SARS-CoV-2 positive pregnancies in peripartum period: A single-center prospective comparative study. These cookies perform functions like remembering presentation options or choices and, in some cases, delivery of web content that based on self-identified area of interests. Five pools collected November 30December 6, representing 59 travelers, had evidence of SGTF. Johansson MA, Wolford H, Paul P, et al. The earliest date of symptom onset was November 15 in a person with a history of international travel. 3501 et seq. Users are referred to the electronic PDF version (https://www.cdc.gov/mmwr) CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination. Multisystem Inflammatory Syndrome in Adults After Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection and Coronavirus Disease 2019 (COVID-19) Vaccination. MMWR Morb Mortal Wkly Rep. Jan 21 2022;71(3):96-102. doi:10.15585/mmwr.mm7103e1, Murthy NC, Zell E, Fast HE, et al. Incubation period of COVID-19 caused by unique SARS-CoV-2 strains: a systematic review and meta-analysis. Update: Characteristics of Symptomatic Women of Reproductive Age with Laboratory-Confirmed SARS-CoV-2 Infection by Pregnancy Status - United States, January 22-October 3, 2020. Aug 2021;38:101019. doi:10.1016/j.eclinm.2021.101019, Groff D, Sun A, Ssentongo AE, et al. If you need to go back and make any changes, you can always do so by going to our Privacy Policy page. BA.2 is a sub-variant of Omicron, which means it is likely that it has a shorter incubation period as well, Oller said. Viral Load The amount of virus that builds up in someone's body is known as. Underlying Medical Conditions and Severe Illness Among 540,667 Adults Hospitalized With COVID-19, March 2020-March 2021. CDC updates and shortens recommended isolation and quarantine period for general population. Reports on incubation periods for BA.5 are sparse. Asymptomatic patients as a source of COVID-19 infections: A systematic review and meta-analysis. Centers for Disease Control and Prevention. As the dominant circulating strain of SARS-CoV-2 evolved from Alpha to Omicron, the incubation period from infection to symptoms or first positive COVID-19 test result gradually decreased, from 5 to 3.4 days, according to a systematic review and meta-analysis published today in JAMA Network Open.. Tables Table 1. One vaccinated patient was hospitalized for 2 days, and no deaths have been reported to date. 2021/08/01/ 2021;46:520-524. doi:https://doi.org/10.1016/j.ajem.2020.11.006, Nasiri N, Sharifi H, Bazrafshan A, Noori A, Karamouzian M, Sharifi A. Ocular Manifestations of COVID-19: A Systematic Review and Meta-analysis. doi:10.1093/cid/ciab338, Wanga V, Chevinsky JR, Dimitrov LV, et al. (16) Both people who have been vaccinated and those who have not been vaccinated can transmit virus. Risk for Stillbirth Among Women With and Without COVID-19 at Delivery Hospitalization - United States, March 2020-September 2021. According to the Australian Department of Health, the incubation period for COVID-19 can range between one and 14 days, with most cases displaying symptoms by day 5 or 6 after exposure. Sect. (15) Images of cutaneous findings in COVID-19 are available from the American Academy of Dermatology. Sect. On November 26, a Presidential Proclamation suspended entry into the United States for noncitizens (as immigrants and nonimmigrants) who were present in any of eight countries in southern Africa (Botswana, Eswatini, Lesotho, Malawi, Mozambique, Namibia, South Africa, and Zimbabwe) during the 14 days preceding travel to the United States. Furthermore, children usually have mild symptoms, and average viral shedding might be less than that of an adult (15). https://www.whitehouse.gov/briefing-room/presidential-actions/2021/11/26/a-proclamation-on-suspension-of-entry-as-immigrants-and-nonimmigrants-of-certain-additional-persons-who-pose-a-risk-of-transmitting-coronavirus-disease-2019external icon, https://www.cdc.gov/quarantine/fr-proof-negative-test.html, *** https://www.cdc.gov/quarantine/order-collect-contact-info.html, https://www.cdc.gov/coronavirus/2019-ncov/php/contact-tracing/contact-tracing-plan/overview.html, https://www.cdc.gov/coronavirus/2019-ncov/your-health/quarantine-isolation.html, https://www.cdc.gov/quarantine/masks/mask-travel-guidance.html, **** https://www.cdc.gov/coronavirus/2019-ncov/travelers/international-travel/index.html. Response to additional COVID-19 vaccine doses in people who are immunocompromised: a rapid review. Jan 2021;21(1):52-58. doi:10.1016/S1473-3099(20)30764-7, Wang J, Kaperak C, Sato T, Sakuraba A. COVID-19 reinfection: a rapid systematic review of case reports and case series. Congestion or runny nose. These cookies perform functions like remembering presentation options or choices and, in some cases, delivery of web content that based on self-identified area of interests. 2020/06/01/ 2020;7(6):e438-e440. 2022;386(8):744-756. doi:10.1056/NEJMoa2116597, Lansbury L, Lim B, Baskaran V, Lim WS. We defined patients in the BA.1dominant period as those who had symptom onset during January 1February 2, 2022. For those without symptoms, CDC guidance states they are considered contagious at least two days before their positive test. Omicron and its subvariants have shorter incubation periods, which means it takes less time for symptoms to appear after exposure to the virus. CDC has developed a working case definition for MIS-A. Meta-analyses of studies published in 2020 identified a pooled mean incubation period of 6.5 days from exposure to symptom onset. Int J Infect Dis.