content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <headerData>
  <submissionType>144</submissionType>
  <filerInfo>
  <filer>
  <filerCredentials>
  <cik>0001873839</cik>
  <ccc>XXXXXXXX</ccc>
  </filerCredentials>
  </filer>
  <liveTestFlag>LIVE</liveTestFlag>
  </filerInfo>
  </headerData>
  <formData>
  <issuerInfo>
  <issuerCik>0001786255</issuerCik>
  <issuerName>Icosavax, Inc.</issuerName>
  <secFileNumber>001-40655</secFileNumber>
  <issuerAddress>
  <street1 xmlns="http://www.sec.gov/edgar/common">1930 Boren Avenue</street1>
  <street2 xmlns="http://www.sec.gov/edgar/common">Suite 1000</street2>
  <city xmlns="http://www.sec.gov/edgar/common">Seattle         </city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">WA</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">98101</zipCode>
  </issuerAddress>
  <issuerContactPhone>206-737-0085</issuerContactPhone>
  <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Adam K. Simpson</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
  <relationshipsToIssuer>
  <relationshipToIssuer>Officer</relationshipToIssuer>
  <relationshipToIssuer>Director</relationshipToIssuer>
  </relationshipsToIssuer>
  </issuerInfo>
  <securitiesInformation>
  <securitiesClassTitle>Common Stock</securitiesClassTitle>
  <brokerOrMarketmakerDetails>
  <name>Morgan Stanley Smith Barney LLC</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">Executive Financial Services</street1>
  <street2 xmlns="http://www.sec.gov/edgar/common">1 New York Plaza 38th Floor</street2>
  <city xmlns="http://www.sec.gov/edgar/common">New York</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">NY</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">10004</zipCode>
  </address>
  </brokerOrMarketmakerDetails>
  <noOfUnitsSold>62205</noOfUnitsSold>
  <aggregateMarketValue>961509</aggregateMarketValue>
  <noOfUnitsOutstanding>50090341</noOfUnitsOutstanding>
  <approxSaleDate>12/20/2023</approxSaleDate>
  <securitiesExchangeName>NASDAQ</securitiesExchangeName>
  </securitiesInformation>
  <securitiesToBeSold>
  <securitiesClassTitle>Common Stock</securitiesClassTitle>
  <acquiredDate>12/20/2023</acquiredDate>
  <natureOfAcquisitionTransaction>Shares acquired upon vesting of restricted stock units</natureOfAcquisitionTransaction>
  <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
  <isGiftTransaction>N</isGiftTransaction>
  <amountOfSecuritiesAcquired>119184</amountOfSecuritiesAcquired>
  <paymentDate>12/20/2023</paymentDate>
  <natureOfPayment>Services Rendered</natureOfPayment>
  </securitiesToBeSold>
  <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
  <remarks>Reflects shares to be sold to cover withholding taxes upon vesting of restricted stock unit awards pursuant to a Rule 10b5-1 instruction letter dated December 6, 2021.</remarks>
  <noticeSignature>
  <noticeDate>12/20/2023</noticeDate>
  <planAdoptionDates>
  <planAdoptionDate>12/06/2021</planAdoptionDate>
  </planAdoptionDates>
  <signature>/s/Adam K. Simpson</signature>
  </noticeSignature>
  </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 3198}]
text: 144
  0001873839
  XXXXXXXX
  LIVE
  0001786255
  Icosavax, Inc.
  001-40655
  1930 Boren Avenue
  Suite 1000
  Seattle
  WA
  98101
  206-737-0085
  Adam K. Simpson
  Officer
  Director
  Common Stock
  Morgan Stanley Smith Barney LLC
  Executive Financial Services
  1 New York Plaza 38th Floor
  New York
  NY
  10004
  62205
  961509
  50090341
  12/20/2023
  NASDAQ
  Common Stock
  12/20/2023
  Shares acquired upon vesting of restricted stock units
  Issuer
  N
  119184
  12/20/2023
  Services Rendered
  Y
  Reflects shares to be sold to cover withholding taxes upon vesting of restricted stock unit awards pursuant to a Rule 10b5-1 instruction letter dated December 6, 2021.
  12/20/2023
  12/06/2021
  /s/Adam K. Simpson