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  <xs:element id="bcrx_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" abstract="false" name="LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_OtherSupplementalInformationRelatedToLeasesTableTextBlock" abstract="false" name="OtherSupplementalInformationRelatedToLeasesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="bcrx_DebtCovenantTermsAxis" abstract="true" name="DebtCovenantTermsAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="bcrx_OperatingLeaseRightOfUseAssetAccumulatedAmortization" abstract="false" name="OperatingLeaseRightOfUseAssetAccumulatedAmortization" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPercentageOfSublicenseRevenueInOtherMarkets" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPercentageOfSublicenseRevenueInOtherMarkets" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesInKeyTerritories" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesInKeyTerritories" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="bcrx_AmortizationOfPremiumDiscountOnInvestments" abstract="false" name="AmortizationOfPremiumDiscountOnInvestments" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_TermLoanTrancheDMember" abstract="true" name="TermLoanTrancheDMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_ProceedsFromIssuanceOfCommonStockIssuedForServices" abstract="false" name="ProceedsFromIssuanceOfCommonStockIssuedForServices" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_DebtCovenantTermsDomain" abstract="true" name="DebtCovenantTermsDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_RoyaltyRate" abstract="false" name="RoyaltyRate" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="bcrx_CollaborativeAndOtherResearchAndDevelopmentMember" abstract="true" name="CollaborativeAndOtherResearchAndDevelopmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_BCX10013Member" abstract="true" name="BCX10013Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_PikInterestPaymentIsMadeMember" abstract="true" name="PikInterestPaymentIsMadeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_WithholdingTaxesAccrued" abstract="false" name="WithholdingTaxesAccrued" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_CollateralForCreditMember" abstract="true" name="CollateralForCreditMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_RPI2019IntermediateFinanceTrustMember" abstract="true" name="RPI2019IntermediateFinanceTrustMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_SharesIssuedCommonStockPremium" abstract="false" name="SharesIssuedCommonStockPremium" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_ClearsideBiomedicalIncMember" abstract="true" name="ClearsideBiomedicalIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_RPI2021And2020IntermediateFinanceTrustMember" abstract="true" name="RPI2021And2020IntermediateFinanceTrustMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_RAPIVABMember" abstract="true" name="RAPIVABMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_LicenseAgreementNumberOfMilestonePayments" abstract="false" name="LicenseAgreementNumberOfMilestonePayments" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesBasedOnReductionInSales" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesBasedOnReductionInSales" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="bcrx_RoyaltyFinancingLiabilitiesCurrent" abstract="false" name="RoyaltyFinancingLiabilitiesCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_LicenseAgreementRoyaltyPaymentNumberOfTiers" abstract="false" name="LicenseAgreementRoyaltyPaymentNumberOfTiers" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="bcrx_RoyaltyFinancingLiabilitiesTableTextBlock" abstract="false" name="RoyaltyFinancingLiabilitiesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="bcrx_LoanAgreementMember" abstract="true" name="LoanAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_TermLoansMember" abstract="true" name="TermLoansMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_AfterThirdAnniversaryMember" abstract="true" name="AfterThirdAnniversaryMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesInOtherMarkets" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesInOtherMarkets" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="bcrx_LesseeOperatingLeaseAssetsAndLiabilitiesTableTextBlock" abstract="false" name="LesseeOperatingLeaseAssetsAndLiabilitiesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="bcrx_RoyaltyFinancingLiabilitiesTextBlock" abstract="false" name="RoyaltyFinancingLiabilitiesTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="bcrx_DebtInstrumentVariableRateFloor" abstract="false" name="DebtInstrumentVariableRateFloor" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="bcrx_AccruedExpensesPolicyTextBlock" abstract="false" name="AccruedExpensesPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="bcrx_TermLoanTrancheAMember" abstract="true" name="TermLoanTrancheAMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_DebtInstrumentCapitalizedInterestRate" abstract="false" name="DebtInstrumentCapitalizedInterestRate" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="bcrx_ScheduleOfReceivablesFromCollaborationsTableTextBlock" abstract="false" name="ScheduleOfReceivablesFromCollaborationsTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="bcrx_ShareBasedPaymentArrangementNumberOfPlans" abstract="false" name="ShareBasedPaymentArrangementNumberOfPlans" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="bcrx_OMERSRoyaltyAgreementMember" abstract="true" name="OMERSRoyaltyAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_InducementPlanMember" abstract="true" name="InducementPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="bcrx_FutureRoyaltiesPayableMember" abstract="true" name="FutureRoyaltiesPayableMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
</xs:schema>
