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  <xs:element id="pcvx_FollowOnPublicOfferingMember" abstract="true" name="FollowOnPublicOfferingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pcvx_IncreaseDecreaseInOperatingLeaseRightOfUseAsset" abstract="false" name="IncreaseDecreaseInOperatingLeaseRightOfUseAsset" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="pcvx_IncreaseDecreaseInAccruedContractManufacturingExpenses" abstract="false" name="IncreaseDecreaseInAccruedContractManufacturingExpenses" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pcvx_PaymentsToAcquireManufacturingFacilityAndEquipment" abstract="false" name="PaymentsToAcquireManufacturingFacilityAndEquipment" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pcvx_ProceedsFromIssuanceOfCommonStockFromFollowOnOfferingNetOfIssuanceCosts" abstract="false" name="ProceedsFromIssuanceOfCommonStockFromFollowOnOfferingNetOfIssuanceCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="pcvx_UnauditedInterimCondensedFinancialStatementsPolicyTextBlock" abstract="false" name="UnauditedInterimCondensedFinancialStatementsPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="pcvx_ScheduleOfInformationRelatedToRightOfUseAssetsAndLeaseLiabilitiesTableTextBlock" abstract="false" name="ScheduleOfInformationRelatedToRightOfUseAssetsAndLeaseLiabilitiesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="pcvx_CashAndCashEquivalentsAmortizedCost" abstract="false" name="CashAndCashEquivalentsAmortizedCost" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pcvx_CashAndCashEquivalentsGrossUnrealizedGainBeforeTax" abstract="false" name="CashAndCashEquivalentsGrossUnrealizedGainBeforeTax" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="pcvx_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAnd12MonthsOrLonger" abstract="false" name="DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAnd12MonthsOrLonger" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pcvx_LonzaCommercialManufacturingAndSupplyAgreementMember" abstract="true" name="LonzaCommercialManufacturingAndSupplyAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pcvx_PatheonCommercialManufacturingAndSupplyAgreementMember" abstract="true" name="PatheonCommercialManufacturingAndSupplyAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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  <xs:element id="pcvx_OperatingLeaseRentAdjustmentPercentage" abstract="false" name="OperatingLeaseRentAdjustmentPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
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  <xs:element id="pcvx_LesseeOperatingLeaseExtendedTermOfContract" abstract="false" name="LesseeOperatingLeaseExtendedTermOfContract" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
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  <xs:element id="pcvx_UpfrontConsiderationInCashAfterAgreementDate" abstract="false" name="UpfrontConsiderationInCashAfterAgreementDate" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="pcvx_LeerinkPartnersLLCMember" abstract="true" name="LeerinkPartnersLLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pcvx_ATMSalesAgreementMember" abstract="true" name="ATMSalesAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pcvx_ATMProgramMember" abstract="true" name="ATMProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pcvx_UnderwrittenPublicOfferingMember" abstract="true" name="UnderwrittenPublicOfferingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pcvx_SaleOfCommonStockAuthorizedAmount" abstract="false" name="SaleOfCommonStockAuthorizedAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pcvx_GrossProceedsFromIssuanceOfCommonStock" abstract="false" name="GrossProceedsFromIssuanceOfCommonStock" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="pcvx_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRightExercised" abstract="false" name="ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRightExercised" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
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  <xs:element id="pcvx_UnvestedEmployeeAndNonEmployeeAwardsMember" abstract="true" name="UnvestedEmployeeAndNonEmployeeAwardsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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  <xs:element id="pcvx_SharesOfCommonStockHeldByMr.PickeringMember" abstract="true" name="SharesOfCommonStockHeldByMr.PickeringMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pcvx_SharesOfCommonStockHeldByTrustMember" abstract="true" name="SharesOfCommonStockHeldByTrustMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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</xs:schema>
