because they were part of an outbreak or were otherwise manually selected for sequencing are excluded. • The chart above shows the proportions of the most common SARS-CoV-2 lineages circulating in Washington grouped in one-week intervals. Proportions are calculated using data which are subject to change over time and will be updated as more data becomes available, including data from prior time periods. Due to the time it takes to complete sequencing, the most recent time period is based on a very small number of sequences and likely to be adjusted over time. To see the national trends, visit the CDC’s variant proportions page. 8 Page Break The table below shows the number of variants of concern (VOC) and variants being monitored (VBM) detected by county of home address since January 2021. VOC VBM County number of sequences and the percent of cases sequenced vary based on several factors including which laboratories conduct the majority of testing in each locality. The map below shows the number of specimens sequenced by county of home address since January 1, 2021. The map below shows the percent of COVID-19 cases with at least one specimen sequenced by county of home address since January 1, 2021. 11 Page break Vaccine Breakthrough Cases A complete report on vaccine breakthrough cases can be found in the reports section of the DOH data dashboard. A vaccine breakthrough case is defined as someone who tests positive for SARS-CoV-2 at least 14 days after their final dose of SARS-CoV-2 vaccine. DOH is monitoring sequencing results for vaccine breakthrough cases. This can help scientists determine whether any specific variants of the virus are causing more breakthrough cases than expected. The table and chart below show vaccine breakthrough cases based on lineages. Lineages not designated as VOC, VOI or VBM are marked as ‘other’. Proportion of variants identified among vaccine breakthrough cases (Breakthrough) with sequencing results compared to variants identified among randomly selected COVID-19 cases (Sentinel) during the same time frame Breakthrough cases by variant table Variant Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Page break Reinfection A complete report on reinfection cases can be found in the reports section of the DOH data dashboard. In general, reinfection means a person was infected once with the virus that causes COVID-19, recovered, and then later became infected again. We are still learning about COVID-19 and the duration and strength of immunity following infection with this virus. Based on what we know from similar respiratory viruses, we expect some COVID-19 reinfections to occur. For disease surveillance purposes, a person with a reported reinfection is an individual with two positive COVID-19 test results (molecular or antigen) reported to DOH where the tests were performed at least 90 days apart. In addition, if genetic sequencing of respiratory samples from a patient’s first (or primary) infection and most recent infection identifies different variants, they are considered a confirmed reinfection regardless of the amount of time between positive tests. Washington State Department of Health adopted this definition on September 1, 2021. DOH is monitoring sequencing results for reinfection cases. This can help scientists determine whether any specific variants of the virus are causing more reinfection cases than expected. The table and chart below show reinfection cases based on lineages. Lineages not designated as VOC, VOI or VBM are marked as ‘other’. Proportion of variants identified among reinfection cases (Reinfection) with sequencing results compared to variants identified among randomly selected COVID-19 cases (Sentinel) during the same time frame. Reinfection cases by variant table Please note - data for the most recent month are incomplete Variant Sep Oct Nov Dec Jan Feb Mar Delta 32 52 46 28 2 2 0 Omicron 0 0 0 234 619 292 83 Other Page break Symptom information Public Health gathers information from patients during interviews and records information about what symptoms people experience during their illness. Not all patients are able to be interviewed, so the symptom status is ‘unknown’ for many cases of illness. When there are a lot of infections, it is more challenging to contact each person, which is why some variants such as Delta have information available for a smaller percentage of cases. Information in the tables below is only presented for variants with at least 100 cases identified. Symptom status by variant VOC VBM Symptoms Delta Omicron Alpha Beta Epsilon Gamma Iota Mu Other* Yes Symptoms by variant among cases reporting symptoms VOC 15 Page break Tracking Omicron Using Clinical Tests WA DOH is tracking the Omicron variant using sequencing. One challenge is that the sequencing process can take up to a few weeks, so we use another testing marker known as ‘S gene target failure (SGTF)’ to identify possible Omicron cases carrying this mutation rapidly and inform public health action. While SGTF does not always mean that a case will be finalized as omicron, greater than 95% of these results are predicted to finalize as omicron. Many laboratories are sharing this data with WA DOH to help track the spread of Omicron. A small number of other SARS-CoV-2 viruses other than Omicron can cause