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Variant; Healthcare system; Vaccines; Diagnostics; Public health

The Omicron variant, like other variants, is comprised of a number of lineages and sub-lineages. The three most common lineages of Omicron currently are BA.1, BA.1.1 and BA.2.The Omicron variant spreads more easily than earlier variants of the virus that cause, including the Delta variant. CDC expects that anyone with Omicron infection, regardless of vaccination status or whether or not they have symptoms, can spread the virus to others. Persons infected with the Omicron variant can present with symptoms similar to previous variants [1]. The presence and severity of symptoms can be affected by vaccination status, the presence of other health conditions, age, and history of prior infection. Omicron infection generally causes less severe disease than infection with prior variants. Preliminary data suggest that Omicron may cause more mild disease, although some people may still have severe disease, need hospitalization, and could die from the infection with this variant. Even if only a small percentage of people with Omicron infection need hospitalization, a large volume of cases in a community could overwhelm the healthcare system which is why it’s important to take steps to protect yourself. vaccines remain the best public health measure to protect people from and reduce the likelihood of new variants emerging. This includes primary series, booster shots, and additional doses for those who need them [2]. Current vaccines protect against severe illness, hospitalizations, and deaths due to infection with the Omicron variant.

However, breakthrough infections in people who are vaccinated can occur. People who are up to date with their vaccines and get are less likely to develop serious illness than those who are not vaccinated and get .Scientists are working to determine how well existing treatments for work. Some monoclonal antibody treatments are less effective against Omicron’s BA, but continue to work against BA.1 and BA.1.1 lineages [3]. Other non-monoclonal antibody treatments remain effective against Omicron. Public health agencies work with healthcare providers to ensure that effective treatments are used appropriately to treat patients. Getting vaccinated and staying up to date with vaccines is the best way to protect yourself and others against the Omicron variant. CDC recommends that everyone 5 years and older protect themselves from by getting vaccinated [4]. Everyone ages 12 years and older should stay up to date on their vaccines and get a booster shot when eligible. Well-fitting masks offer protection against all variants. In general, people do not need to wear masks when outdoors. If you are sick and need to be around others, or are caring for someone who has, wear a mask. If the Community Level where you live is, wear a mask based on your personal preference, informed by your personal level of risk [5]. If you are at risk for severe illness, talk to your healthcare provider about wearing masks indoors in public. If you live with or will gather with someone at risk for severe illness, wear a mask when indoors with them. If you are 2 or older, wear a well-fitting mask indoors in public, regardless of vaccination status or individual risk. If you are at risk for severe illness, wear a mask or respirator that provides you with greater protection. Tests can tell you if you have. Learn how to get tested. Two types of tests are used to test for current infection: nucleic acid amplification tests and antigen tests. NAAT and antigen tests can tell you if you have a current infection [6].

Self-tests can be used at home or anywhere, are easy to use, and produce rapid results. If your self-test has a positive result, isolate and talk to your healthcare provider. If you have any questions about your self-test result, call your healthcare provider or public health department. Individuals can use CDC’s Viral Testing Tool to help determine what kind of test to seek. Your test result will only tell you if you do or do not have. It will not tell you which variant caused your infection [7]. Visit your state, tribal, local, or territorial health department’s website for the latest local information on testing. It is important to use all tools available to protect yourself and others. CDC scientists are working with partners to study data and virus samples that may answer important questions about the Omicron variant. CDC will provide updates as new information becomes available. In the United States, CDC uses viral genomic surveillance to track variants, to more quickly identify and act upon these findings to best protect the public’s health. CDC established multiple ways to connect and share viral genomic sequence data being produced by CDC, public health laboratories, and commercial diagnostic laboratories within publicly accessible databases maintained by the NCBI and the Global Initiative on Sharing Avian Influenza Data external icon GISAID. Systems have been established to detect signals of potential VOC’s or variants of interest and assess these based on the risk posed to global public health.6 A variant of with a D614G substitution in the gene encoding the spike protein emerged in late January or early February 2020. Over a period of several months,the D614G mutation replaced the initial strain identified in China and by June 2020 became the dominant form of the virus circulating globally. Studies in human respiratory cells and in animal models demonstrated that compared to the initial virus strain, the strain with the D614G substitution has increased infectivity and transmission. The virus with the D614G substitution does not cause more severe illness or alter the effectiveness of existing laboratory diagnostics, therapeutics, vaccines, or public health preventive measures [8]. In August and September 2020, a variant linked to infection among farmed mink and subsequently transmitted to humans, was identified in North Jutland, Denmark. The variant, referred to as the cluster 5 variant by Danish authorities, has a combination of mutations not previously observed. Preliminary studies conducted in Denmark, suggests that this variant may result in reduced virus neutralization in humans, which could potentially decrease the extent and duration of immune protection following natural infection or vaccination. First, available information allows for the delineation of VOC B.1.617. B.1.617 viruses are divided in three lineages: B.1.617.1, B.1.617.2 and B.1.617.3. Available findings for lineages B.1.617.1 and B.1.617.2 were initially used to designate B.1.617 a global VOC on 11 May 2021. Since then, it has become evident that greater public health risks are currently associated with B.1.617.2, while lower rates of transmission of other lineages have been observed. To reflect this updated information, B.1.617 has been delineated as follows.B.1.617.2 remains a VOC and labelled variant delta – this variant showed increased transmissibility and a growing number of countries reporting outbreaks associated with this variant. Further studies to assess the impact of this variant remain a high priority. B.1.617.1 has been reclassified to a VOI and labelled variant kappa – while also demonstrated increased transmissibility (in specified locations), global prevalence appears to be declining. This variant will continue to be monitored and reassessed regularly. B.1.617.3 is no longer classified as either a VOI or VOC – relatively few reports of this variant have been submitted to date [9]. Second, variant B.1.616, which was first detected in France following investigations into an unusual cluster of cases in a hospital, is no longer classified as a VOI. Local authorities have reported that the outbreak has been controlled and no further detections within or outside of France have been reported since late-April 2021. Further local and regional monitoring remains prudent, given B.1.616 was associated with potential increased disease severity and reduced detections via nasopharyngeal samples. As of 20th July 2021 update by WHO, the number of countries/areas/territories reporting has continued to increase, 180 countries are reporting alpha variant, 130 countries, territories and areas reporting beta variants, whereas for gamma and delta the cases have spread to 78 and 124 countries/territories and areas respectively. On 14th December 2020, UK authorities have confirmed a variant referred to as alpha-B1.1.7 [10].This variant contains 23 nucleotide substitutions and is not phylogenetically related to the virus circulating in the UK at the time the variant was detected. Variant initially appeared in South East England but within a few weeks began to replace other virus lineages in the same geographic area and London.

Mutations in the spike protein, which aids the virus in its effort to invade human cells. These single mutations occur in a part of the virus RNA that causes a change in a particular building block leading to increased transmission which allows binding more readily to the human receptor angiotensin converting enzyme-2, the entry point for to a wide range of human cells. This variant has been identified from routine sampling and genomic testing conducted across the UK. Preliminary epidemiologic, modelling, phylogenetic and clinical findings suggest that new variant has increased transmissibility. However, preliminary analyses also indicate that there is no change in disease severity, or occurrence of reinfection between variant cases compared to other viruses circulating in the UK. Laboratory evaluation has demonstrated no significant impact on the performance of antigen based lateral flow devices. As on 30th December, variant has been reported in 31 other countries/territories/areas in five of the six WHO regions.

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